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UNIV.QI 
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IMPERIAL INSTITUTE 

MONOGRAPHS ON MINERAL RESOURCES 

WITH SPECIAL REFERENCE TO THE 

BRITISH EMPIRE 

PREPARED UNDER THE DIRECTION OF THE 
MINERAL RESOURCES COMMITTEE WITH THE 
ASSISTANCE OF THE SCIENTIFIC AND TECH 
NICAL STAFF OF THE IMPERIAL INSTITUTE 

LEAD ORES 

BY T. C. F. HALL, M.Inst.M.M., F.G.S. 




LONDON 

JOHN MURRAY, ALBEMARLE STREET, W. 

1921 



THE IMPERIAL INSTITUTE MAP OF 
THE CHIEF SOURCES OF METALS 
IN THE BRITISH EMPIRE, WITH 
DIAGRAMS OF PRODUCTION FOR 1915 

This Map and Diagrams, prepared at the Imperial 
Institute with the advice of the Mineral Resources Com- 
mittee, show the chief British Countries of occurrence and 
production of metallic ores, and the relation of their 
outputs to those of other countries of the world. 

Price 5s. 6d. (post free from the IMPERIAL INSTITUTE, 
London, S.W.y) mounted on linen and tolded. 



IMPERIAL INSTITUTE MONOGRAPHS 

ON MINERAL RESOURCES WITH 

SPECIAL REFERENCE TO THE 

BRITISH EMPIRE 



MANGANESE ORES 

By A. H. CURTIS, B.A., M.lNsx.M.M., A.M.I.C.E., 
F.G.S. 3s. 6d. net 

TIN ORES 

By G. M. DAVIES, M.Sc. (LoND.), F.G.S., 3s. 6d. net 

TUNGSTEN ORES 

By R. H. RASTALL, M.A., and W. H. WILCOCKSON, 
M.A., F.G.S. 3s. 6d. net 

COAL 

By J. H. RONALDSON, M.I.M.E., M.lNsx.M.M., 
F.G.S. 6s. net 

PLATINUM METALS 

By A. D.LUMB, A.R.S.M., F.G.S., ASSOC.INST.M.M., 

3s. 6d. net 

LEAD ORES 

By T. C. F. HALL, M.lNST.M.M. 6s. net 

In Preparation 

CHROMIUM; POTASH; COPPER; MOLYBDENUM 
AND VANADIUM; SILVER; PETROLEUM; ETC. 



IMPERIAL 



MONOGRAPHS ON MINERAL RESOURCES 

WITH SPECIAL REFERENCE TO THE 

BRITISH EMPIRE 



EMo, 

IMPERIAL INSTITUTE 

MONOGRAPHS ON MINERAL RESOURCES 

WITH SPECIAL REFERENCE TO THE 

BRITISH EMPIRE 

PREPARED UNDER THE DIRECTION OF THE 
MINERAL RESOURCES COMMITTEE WITH THE 
ASSISTANCE OF THE SCIENTIFIC AND TECH- 
NICAL STAFF OF THE IMPERIAL INSTITUTE 

LEAD ORES 



BY 

T. C. F. HALL, M.Inst.M.M., F.G.S. 




LONDON 

JOHN MURRAY, ALBEMARLE STREET, W. 

1921 



ALL RIGHTS RESERVED 



IMPERIAL INSTITUTE 
MINERAL SECTION 

THE Imperial Institute is a centre for the exhibition and 
investigation of minerals with a view to their commercial 
development, and for the supply of information respecting the 
sources, composition and value of minerals of all kinds. 

The Imperial Institute is provided with Research Labora- 
tories for the investigation, analysis and assay of minerals, 
and undertakes reports on the composition and value of minerals 
for the information of Governments and producing companies 
and firms, in communication with the principal users in the 
United Kingdom and elsewhere in the Empire. 

Important minerals from within the Empire are exhibited 
in the respective Courts of the Public Exhibition Galleries, 
and also in the Mineral Reference Collections of the Institute. 

A special staff is engaged in the collection, critical revision 
and arrangement of all important information respecting 
supplies of minerals especially within the Empire, new methods 
of usage and other commercial developments. 

Articles on these and related subjects are periodically 
published in the Bulletin of the Imperial Institute, and Mono- 
graphs on special subjects are separately published under the 
direction of the Committee on Mineral Resources. 



IMPERIAL INSTITUTE 
Advisory Committee on Mineral Resources 

The Right Hon. VISCOUNT HARCOURT, D.C.L. (Qhairman). 
*AdmiraI SIR EDMOND SLADE, K.C.I.E., K.C.V.O. (nominated by 

the Admiralty), (Vice-Qhairman). 
EDMUND G. DAVIS, Esq. 
*WYNDHAM R. DUNSTAN, Esq., C.M.G., LL.D., F.R.S,, Director 

of the Imperial Institute. 
J. F. RONCA, Esq., M.B.E., A.R.C.S., Department of Industries 

and Manufactures (nominated by the Board of Trade). 
*Professor J. W. GREGORY, F.R.S., Professor of Geology, University 

of Glasgow, formerly Director of Geological Survey, Victoria, 

Australia. 
Sir ROBERT HADFIELD, Bart., F.R.S., Past-President, Iron and 

Steel Institute. 
Captain A. L. ELSWORTHY, Intelligence Department, War Office 

(nominated by the War Office). 

W. W. MOYERS, Esq. (Messrs. A. Watson & Co.), Liverpool. 
R. ALLEN, Esq., M.A., B.Sc., Imperial Institute (Secretary). 
Members of Editorial Sub-Committee. 

MINERAL SECTION 

Principal Members of Staff 

Superintendent 
R. ALLEN, M.A. (Cantab.), B.Sc. (Lond.) M.Inst.M.M. 

Assistant Superintendent 
S. J. JOHNSTONE, B.Sc. (Lond.), A.I.C. 

Senior Assistant 
W. O. R. WYNN, A.I.C. 

Assistants 

S. BANK. A. T. FAIRCLOTH. 

F. H. BELL. R. C. GROVES, M.Sc. (Birm.). 

H. BENNETT, B.Sc. (Lond.). E. HALSE, A.R.S.M., M.Inst.M.M. 

vi 



PREFACE 

THE Mineral Resources Committee of the Imperial Institute 
has arranged for the issue of this series of Monographs on 
Mineral Resources in amplification and extension of those 
which have appeared in the Bulletin of the Imperial Institute 
during the past fifteen years. 

The Monographs are prepared either by members of the 
Scientific and Technical Staff of the Imperial Institute, or by 
external contributors, to whom have been available the 
statistical and other special information relating to mineral 
resources collected and arranged at the Imperial Institute. 

The object of these Monographs is to give a general account 
of the occurrences and commercial utilization of the more 
important minerals, particularly in the British Empire. No 
attempt has been made to give details of mining or metal- 
lurgical processes. 

HARCOURT, 

Chairman, Mineral Resources Committee. 



IMPERIAL INSTITUTE, 

LONDON, S.W.y. 

October 1920. 



vii 



CONTENTS 
CHAPTER I 

PA8 

LEAD ORES : THEIR OCCURRENCE, CHARACTERS 

AND USES i 

CHAPTER II 
SOURCES OF SUPPLY OF LEAD ORES 

(a) BRITISH EMPIRE : 

Europe : United Kingdom .... 40 

Asia : India ....... 61 

Africa : Egypt ; Nigeria ; Rhodesia ; South- 
West Protectorate ; Sudan ; Union of South 
Africa ....... 62 

North America: British West Indies ; Canada; 

Newfoundland ...... 65 

Australasia : New South Wales ; Queensland ; 
South Australia ; Victoria ; West Australia ; 
Tasmania ; New Zealand . ." -7 

CHAPTER III 
SOURCES OF SUPPLY OF LEAD ORES 

(b) FOREIGN COUNTRIES : 

Europe : Austria ; Belgium ; Bulgaria ; Czecho- 
slovakia ; France ; Germany ; Greece ; 
Hungary ; Italy ; Norway ; Poland ; Por- 
tugal ; Russia ; Spain ; Sweden ; Upper 
Silesia ; Yugo-Slavia - ... 78 

Asia : Asia Minor; China; Indo-China ; Japan 99 

Africa : Algeria ; Tunis 103 

North America : Mexico ; United States . . 103 
South America : Argentine ; Bolivia ; Chile ; 

Colombia; Peru ..... 120 

APPENDIX : LEAD POISONING 121 

WORLD MAP OF LEAD DEPOSITS .... 122 
REFERENCES TO LITERATURE ON LEAD . . . 123 



NOTE : Numerals in square brackets in the text refer to the 
Bibliography at the end. 



LEAD ORES 

CHAPTER I 
LEAD ORES : THEIR OCCURRENCE, CHARACTERS AND USES 

INTRODUCTION 

LEAD, although one of the commoner of the base metals, is 
present in the earth's crust only to the extent of a fraction 
of i per cent, of the whole. In workable deposits, however, 
the proportion is much higher owing to a natural concentration 
of material. Lead is closely associated in nature with zinc, 
and their primary or sulphide ores commonly occur together. 
Zinc ores are more soluble than lead ores, hence in the zone 
of oxidation the former have frequently been leached away, 
and practically pure lead ore may occur above water-level. 
In this way were formed the lead carbonate deposits of Lead- 
ville and elsewhere. Such bodies, however, give place to 
mixed lead and zinc sulphides in depth. Lead in nature 
is also intimately associated with silver, and many lead 
deposits are also the repositories of valuable silver ores. 
Galena itself is frequently argentiferous and may be regarded 
as the chief source of the world's supply of silver. ' 

Owing to this association a large number of deposits are 
conveniently referred to collectively as silver-lead-zinc de- 
posits. The vertical distribution of the ores of the different 
metals suggests that the deposition of zinc takes place under 
conditions of higher temperature and pressure than those of 
lead, whilst silver is more closely associated with the latter 
metal than with the former. The ores thus tend to occur in 
zones, though their limitation is necessarily very irregular 
and subject to considerable overlapping. Zinc, as a general 



2 LEAD ORES 

rule, predominates in the lower zone of mineralization, 
below the main lead occurrence, while silver occurs more 
particularly in the upper zone, although, in small quantity, it 
may be generally distributed with the other metals. 

The predominant mineral in a deposit of this class will 
depend, therefore, upon the extent to which the original ore 
body has been eroded. Thus we may regard those deposits 
carrying large bodies of rich silver ores (often accompanied 
by gold) with only subordinate amounts of galena as represent- 
ing a more superficial or later type of mineralization than 
is the case with others carrying chiefly lead or zinc. Such 
deposits are a marked feature of the American Cordilleran 
region, where they are associated chiefly with Tertiary lavas, 
rocks which, comparatively speaking, have undergone but 
little erosion since their formation at a late geological period. 
The contained veins may well represent, therefore, the upper 
zone of a mineral sequence characterized by the predominance 
of lead and zinc at greater depths. Indeed, in many of these 
veins the mining of lead has succeeded that of silver. Con- 
versely, it has been suggested that there is good evidence for 
believing that the well-known lead-bearing veins of the Frei- 
berg district represent deeper portions of similar deposits, 
the upper parts of which have been eroded away. Again, 
it is common knowledge that many deposits formerly worked 
for lead ore have, with increased depth, produced mainly 
zinc ore. 

It is obvious that the vertical distribution of the metals 
and the limitation of their ores to particular horizons is of 
great economic significance. It is especially a subject for 
careful consideration in connection with the re-opening of 
old mines. 

LEAD-BEARING MINERALS 

. Lead as a native metal is of exceedingly rare occurrence, 
and is always of a secondary nature, having been reduced 
from some pre-existing compound. 

The principal ore is the sulphide, galena. Other ores 
occurring in sufficiently large quantities to be mined are 
cerussite and anglesite, but these belong to the oxidized or 



THEIR OCCURRENCE, CHARACTERS AND USES 3 

superficial zone. A basic sulphate containing lead and iron, 
plumbojarosite, though a rare mineral, occurs in certain mines 
in Utah in sufficient abundance to be mined [78]. The red 
oxide, minium, Pb s O 4 , and the yellow oxide, massicot, PbO, 
are comparatively rare minerals. The phosphate of lead, 
pyromorphite, 3Pb 3 (P0 4 ) 2 PbCl 2 , and the arsenate, mimetite, 
3Pb 3 (As0 4 ) 2 PbCl 2 , (green lead ores), commonly occur with 
other secondary lead minerals, although usually only in 
small quantity. The closely allied vanadate, vanadinite, 
3Pb 3 (VO 4 )oPbCl 2 , may be regarded as an ore of vanadium. 
The following are of occasional occurrence : the chromate, 
crocoisite, PbCr0 4 , the molybdate, wulfenite, PbMo0 4 , and 
the tungstate, stolzite, PbW0 4 . In addition to the above there 
are numerous other lead-bearing minerals, including tellurides, 
selenides, oxy chlorides, silicates, etc., which are of mineralogical 
interest only ; and of recent formation are the group of oxy- 
chlorides (lanrionite, etc.) which have been formed by the action 
of sea- water on the ancient slag-heaps of Laurium, in Greece. 

Galena. Lead sulphide, PbS (Pb 86-6 per cent). This, the 
common ore of lead, is of a lead-grey colour, and has a bright 
metallic lustre on fracture. It crystallizes in the cubic system, 
and has a perfect cubic cleavage. It is often massive in granu- 
lar aggregates. A finely granular form, known as steel ore, 
probably results from secondary deposition, and is frequently 
rich in silver. Hardness = 2-5 ; specific gravity = 7-5. 

Silver is always present in galena, but the quantity greatly 
varies and some ores contain only traces, though the amount 
is seldom less than o-oi per cent. It may reach 0-25 per 
cent, or even higher. It may be stated generally that galena 
in large crystals, or in coarse grains, is usually poor in silver, 
while galena in small crystals, or in fine grains, is frequently 
rich in silver. The quantity of silver present is usually 
reckoned in ounces troy per ton of ore, and ores averaging 
30 oz. * or over per ton are considered valuable, and known as 
argentiferous ores. Argentiferous galena sometimes contains 
gold. Other impurities found in galena are zinc, cadmium, 
iron, copper and antimony. Besides blende pyrite and 
chalcopyrite are frequent associates. Although galena is less 
* About o 1 1 per cent. 



4 LEAD ORES 

prone to alteration than most sulphides, it may be accom- 
panied in the oxidation zone by cerussite, anglesite, pyro- 
morphite, etc., or even may be entirely replaced by the first 
two minerals. 

Jamesonitc, zPbS.Sb^ (Pb 50-8, Sb 29-5 per cent.), bou- 
langerite, 5PbS,2Sb 2 S, (Pb 55-4, Sb 22-8 per cent.), and 
bonrnonite, 3(PbCu s )S.Sb 2 Sj (Pb 42-6, Sb 247 per cent.), are 
lead-antimony minerals, but the last, containing 13 per cent, of 
copper, is sometimes mined as an ore of copper. Jamesonite, 
associated with arsenopyrite, pyrrhotite and blende, occurs as 
a replacement of limestone at Zimapan, in Mexico [59]. 

Cerussite, or white lead ore, PbCO s (Pb 77-5 per cent.). 
This ore the carbonate often occurs in considerable masses, 
associated with oxides of iron and manganese. It is colour- 
less to white or grey, often translucent, with a brilliant 
adamantine lustre. It crystallizes in the orthorhombic system, 
and occurs usually in prismatic crystals, often forming fibrous 
and radiating aggregates with a silky appearance. It is 
found also in granular or compact masses. It is very brittle. 
Hardness, 3 to 3-5 ; specific gravity, 6-5. 

It was formerly the principal ore at Leadville (Colorado), 
and has been found in considerable bodies in Pima county 
(Arizona), Cceur d'Alene (Idaho), Broken Hill (N.S.W.) and 
Mexico (Sierra Mojada, Santa Eulalia, etc.). 

Anglesite, or lead vitriol, PbSO 4 (Pb 68-3 per cent.). This 
mineral has a more resinous lustre, and is softer and lighter 
than cerussite. Hardness, 2-7 to 3 ; specific gravity, 6-3. 
Its crystals are usually tabular or pyramidal. It is rarer 
than cerussite, and is readily transformed into the carbonate. 
Considerable quantities have been obtained from Leadville, 
Arizona, California and Mexico (Campo Morado, etc.). It 
was first found by Withering at the Parys Mine, Anglesea, 
from which place it takes its name. 

x, 

GENESIS AND MODE OF OCCURRENCE OF LEAD ORES 

Lead ores occur in veins and lodes ; as metasomatic replace- 
ments, mainly in limestone and dolomite ; as contact deposits ; 
and as disseminations in sandstone and shale. The last- 



THEIR OCCURRENCE, CHARACTERS AND USES 5 

named are comparatively unimportant. It has been esti- 
mated that about half the world's production of lead ore 
comes from metasomatic deposits. 

Vein deposits. In these the ore occurs in infilled fissures, 
which served as channels for the circulation of lead-bearing 
solutions from magmatic or other sources. Frequently, how- 
ever, the vein filling is accompanied by considerable replace- 
ment of the country rock. The distribution of the ore in the 
fissures is often closely related to the character of the enclos- 
ing rock. Thus at Snailbeach Mine, Shropshire, the ore- 
shoots occur in grit, and there is complete impoverishment in 
soft shale, which occurs in bands alternating with the former 
rock. Again, in the north of England the lodes are lead- 
bearing in limestone and chert, and to a much less extent in 
sandstone, but are rarely productive in shale. Lead veins 
vary in width from a few inches to several feet, and some 
have been traced for miles, though this must be regarded as 
exceptional. Many have been worked to a depth of several 
thousand feet. 

As already pointed out, lead veins almost invariably carry 
zinc ore as well, principally in depth. Other associations are 
pyrite and chalcopyrite, and the gangues are quartz, calcite, 
dolomite, siderite, fluorspar or barytes. These minerals are 
subject to much local variation and one, to the more or less 
exclusion of the others, is usually characteristic of a particular 
district or group of veins. Quartz is found especially in those 
veins which carry much chalcopyrite, and, when much silver 
is present, the gangue is characteristically a carbonate or 
barytes. 

As galena is highly insoluble it may occur with but little 
alteration up to the surface, but under special conditions 
considerable quantities of carbonate (cerussite) or of sulphate 
(anglesite) may be found. Such ores, however, occur more 
especially in limestone replacement deposits, where the con- 
ditions for deep oxidation are more favourable. Where the 
galena carries much silver, an enrichment of this metal in the 
secondary zone is often a conspicuous feature, and native 
silver may occur upon the fractures and surfaces of the 
galena. Rich silver ores also may be present. 






6 LEAD ORES 

Metasomatic deposits. These constitute a very important 
class and contribute, at the present time, by far the greater 
part of the world's output of lead ore. These deposits have 
been considerably developed in the United States of America, 
where many of them are of large dimensions and furnish some 
of the most remarkable occurrences of lead ore known. 

This type of ore body has been formed by a replacement of 
limestone or .dolomite by galena, the sulphide of lead having 
most probably been carried in solution by alkaline sulphides. 
The ore may occur disseminated through the limestone, but 
generally favours certain beds or horizons, and tends to be 
located in the neighbourhood of fissures, joints or bedding- 
planes. The contact of an impervious bed or igneous intru- 
sion is commonly the site of maximum deposition. Deposits 
of this nature are notoriously irregular, so that their mining 
is attended with considerable uncertainty, and a thorough 
knowledge of the geological structure is essential to their 
successful exploitation. Although they occur almost invari- 
ably in limestone or dolomite, they are found also in quartzite 
and shale, though in such cases the replacement is usually 
very incomplete. 

As in the case of veins, these deposits carry both galena 
and blende, the latter chiefly in depth. The galena has 
usually a high silver content, and rich silver ores, such as 
native silver, argentite and various sulpho- salts, are often a 
feature of the upper zones. Gold is found also. 

These ore bodies are remarkable for an extensive develop- 
ment of oxidized ores, and the zone of oxidation is often deep, 
yielding large quantities of carbonate and sulphate ores. In 
many deposits this zone has been the main source of the lead, 
the primary ore having a preponderance of blende. 

Gangue minerals are few ; dolomite and allied carbonates 
are common, and cherty quartz, or " jasperoid," is charac- 
teristic. Calcite, barytes, fluorspar and, more rarely, rhodo- 
crosite are found also. 

The majority of these deposits have evidently been formed 
by ascending hydrothermal solutions, though their connec- 
tion with igneous rocks is not always obvious. Certain ores, 
however, like those of Missouri, appear to have been derived 



THEIR OCCURRENCE, CHARACTERS AND USES 7 

from the action of atmospheric waters circulating at shallow 
depths. 

Some of the most remarkable deposits of this nature occur 
in the Cordilleran region of America, one of the best known 
being that of Leadville, Colorado, so ably described by 
Emmons : his opinion of the genesis is not now accepted [i]. 

Contact deposits. Metallic deposits occurring at the con- 
tacts of intrusive igneous masses are known in many places, 
and though galena is perhaps the least abundant of all the 
sulphides occurring in this manner, there are several well- 
known instances of this character. Such deposits are best 
developed where the rocks bordering the intrusion are of 
sedimentary origin, especially limestone ; and the ores occur 
as a metasomatic replacement of the enclosing rock, extending 
outwards for varying distances from the contact. The deposits 
may be quite irregular, but where they tend to follow certain 
horizons are often tabular. 

When galena occurs it is invariably accompanied by 
blende, this mineral, indeed, being of chief importance, and 
almost always present in deposits of this nature. Pyrite, chal- 
copyrite and magnetite are common accompaniments. The 
gangue minerals comprise such typical contact metamorphic 
varieties as garnet, epidote, actinolite, etc. 

The best-known deposit of this class is furnished by the 
Magdalena Mines, in New Mexico, worked for lead, zinc and 
silver. By some the celebrated Broken Hill lode is con- 
sidered a contact deposit, but this is doubtful ; formerly it 
was regarded as a saddle reef [79], [80]. 

Disseminations. Ores of lead, usually associated with those 
of copper and sometimes vanadium, are found disseminated 
in certain sandstones and shales. The containing rocks are 
almost invariably of Permian or Triassic age, and form parts 
of a thick series of strata of lacustrine or shallow-water for- 
mation. The ores tend to follow certain beds or horizons in 
the series, particularly those rich in carbonaceous matter and 
plant remains, but are by no means confined to these. They 
often occupy small fissures. Their general mode of occurrence 
suggests that concentration has taken place after the deposi- 
tion of the containing strata, and it appears likely that the 
2 



8 LEAD ORES 

ores owe their origin to the leaching effect of atmospheric 
waters upon the finely disseminated metallic content of rocks 
accumulated rapidly under arid conditions. They show no 
connection with any form of igneous activity. 

So far as lead is concerned the chief minerals in these 
deposits are galena and cerussite ; with these are usually 
associated more or less pyrite and various ores of copper ; 
in fact, generally speaking, this class of deposit is of more 
importance as a source of copper than of lead. Interesting 
occurrences are various copper and lead vanadates, and the 
ores frequently contain small amounts of nickel, cobalt, 
molybdenum and selenium. Gangue minerals are uncommon, 
and comprise small amounts of barytes, calcite and gypsum. 

These deposits are of low grade and can only be profitably 
mined under favourable conditions. The best-known lead 
occurrence is in the Triassic sandstone at Commern and 
Mechernich, near Aix-la-Chapelle. 

TENOR OF LEAD ORES 

The percentage of metal in crude lead ore naturally varies 
considerably in different localities, and it is not possible to 
give any precise details regarding the grade which is neces- 
sary for profitable mining, since this will obviously depend 
upon local conditions and the current price of the metal. The 
nature of the deposit and the consequent methods of mining 
it, the character of the ore and the conditions of labour 
and transport, are all factors which must be taken into 
consideration. 

The mining of argentiferous lead ores has been greatly 
influenced by the price of silver, and the value of such 
deposits has been subject to considerable variation with 
fluctuations in the price of that metal. 

In certain deposits, such as some of those of the American 
Cordilleran region, ore has been mined of sufficiently high 
grade to be sent direct to the smelters without further treat- 
ment, but such bonanzas may be very short-lived, and a 
high-grade deposit of an irregular and limited character is 
often less valuable in the aggregate than a low-grade 
deposit of a persistent and regular nature. Thus in Mis- 



THEIR OCCURRENCE, CHARACTERS AND USES 9 

souri, low-grade ores, having a recoverable lead content of 
on ly 3'5 P er cent., are successfully mined with a large and 
steady output, which amounts to over 5,000,000 tons of 
crude ore per annum. In the Cceur d'Alene district of Idaho 
similar conditions prevail, though the ore there is of higher 
grade. On the other hand, the industries founded on the 
spectacular deposits of Colorado and Nevada, for example, 
had a rapid rise and fall, and at the present time these 
deposits are comparatively unimportant. 

CONCENTRATION OR DRESSING OF LEAD ORES 

Only an insignificant amount of lead ore is mined in a 
sufficiently pure state to need no further treatment, except 
perhaps hand-picking, before being sent to the smelters. 
Almost invariably the crude ore has to be crushed and sub- 
jected to a process of dressing or concentration for the re- 
moval of the waste material, which, in the case of a low-grade 
ore, may be present in considerable quantity. In the low- 
grade ores of Missouri, for example, the concentrate obtained 
amounts only to a little over 5 per cent, of the total ore mined. 

The degree of concentration varies considerably in different 
places according to the nature of the ore and the methods 
employed, but is seldom, if ever, ideal. A lengthy and very 
thorough system of dressing operations may result in a finished 
product of considerable purity, but nevertheless may be 
uneconomical and attended by considerable loss of lead, so 
that it becomes undesirable to carry the process to completion. 
Absolute purity is indeed practically unobtainable. 

The dressing of the ore has for its object the removal of not 
only the gangue minerals, such as quartz, calcite, fluorspar, 
barytes, etc., but also of any compounds of the base metals- 
zinc, copper, iron, antimony, etc. which otherwise have to 
be removed during smelting and refining. Owing to their 
comparatively low specific gravity the gangue minerals can 
usually be effectively separated from the crushed ore by 
ordinary wet gravity methods, assisted by mechanical devices 
(jigs, shaking tables, etc.), and the same remark applies to 
blende, the common associate of galena, when in a moderately 
coarse state. In cases where the association is of a more 



10 



LEAD ORES 



intimate and fine-grained character, as at Broken Hill, N.S.W., 
the employment of flotation processes becomes needful. 

The concentrates produced at various mines differ consider- 
ably in grade, for while in some the metallic content is under 
50 per cent., in others it is as high as 75 per cent, or over. 
The average recoverable lead content of the concentrates pro- 
duced in the United Kingdom may be taken at about the latter 
amount. 

The following tables [4/p. 50] give (i) the tenors of various 
ores before and after dressing, and (2) analyses of the ore and 
of the various grades of concentrate produced in south-east 
Missouri : 

Metallic Contents of Various Lead Ores and of the Resulting 

Concentrates 







Dressed ore. 




Raw ore 




Locality. 


per cent. 
Lead. 


Per cent. 


Oz. silver per 






Lead. 


ton. 


St. Joseph, Missouri 
North of England 










8-5 


70 
70-77 


8-00 


Bleiberg, Carinthia 










8 


71 


0-05 


Przibram, Bohemia 










20 


37-38 


76-50 


Freiberg, Saxony 










3 


18-70 


17-88 


Tarnowitz, Silesia 










6 


75-5 


I3-50 


Upper Harz, Prussia 










9 


64 


25-00 


Mechernich, Prussia 










2 


56-60 


3-4 


Kellogg, Idaho . 










II 


60 


30-00 



Analyses of the Ore and the Various Concentrates produced in 
South-East Missouri 






Ag.(a) 


Cu. 


Pb. 


SlOj. 


Fe. 


AL0 3 . 


CaO. 


MgO. 


Zn. 


s. 


NI&CO. 


Ore 


0-12 


0-06 


5'7 


5-o 


4'l 


4'9 


25-5 


I 4 -2 


0-8 


2-O 





High-grade 
























concentrate 


0-7 


0-13 


73-2 


I-O 


3-5 





2-6 


0-8 


0-4 


15-0 


0-O5 


Medium con- 
























centrate 


i-3 


O-I2 


68-6 


i-4 


4-6 





3'i 


i'4 


0-8 


15-5 


0-O6 


Low-grade con- 
























centrate 


i-o 


0-30 


65-8 


o-5 


3'i 


0-5 


4'3 


2-8 


1-7 


13-7 





Flotation 
























slime 





0-50 


45-o 


9-6 


4'4 


3'i 


7'5 


4'2 


4-0 


12-3 





Do. high- 
























grade . 


3-7 


0-05 


57-8 


6-0 


2-7 





2-2 


1-4 


9-4 


15-5 





Joplin concen- 
























trate . 


" 


~~ 


80-2 


i-i 


I-O 




0-4 




1-7 


13-3 





(a) Ounces per ton. 



THEIR OCCURRENCE, CHARACTERS AND USES n 

VALUATION OF LEAD ORES 

The value of a lead ore to the smelter is dependent upon 
two main factors, namely, the value of the contained metal 
and the cost of obtaining it. Broadly speaking, the price 
paid for an ore will be the value of the net metallic yield 
minus the total cost of treatment and the profit it is desired 
to make. But there are other considerations influencing the 
sale. Thus the quality and quantity of ore offered are 
important items, and smelters carrying large stocks make a 
deduction from the market quotation of the metal in order 
to afford protection against loss due to fluctuation in the 
market price. In estimating the metallic yield of an ore 
deductions are made for certain and possible losses during 
smelting, and, as mentioned above, smelters as a rule cover 
themselves against unavoidable losses by only paying for 
90 per cent, of the lead content of the ore. 

The cost of treatment of an ore naturally varies with its 
character and the methods employed. Carbonate ores, for 
example, command a higher price than sulphide ores, since 
the latter must be roasted, a process often involving con- 
siderable loss of metal. The nature of the gangue is an all- 
important factor, and according to the composition of this an 
ore may be self- fluxing, acid or basic. The first named, re- 
quiring little or no fluxes, will naturally command a better 
price than those to which foreign material has to be added 
in order to form a desirable slag, as is the case with acid and 
basic ores. Since most ores are siliceous, basic ores are likely 
to experience a ready demand. 

The price of an ore is affected by the impurities present in 
it. Substances such as sulphur, arsenic, antimony, zinc, 
magnesium and aluminium, if present above certain percen- 
tages, are charged for, since they cause losses or difficulties 
during smelting, or may render the lead impure. On the 
other hand, for silver, gold and copper, when present above 
certain amounts, payment is made. This is also the case 
with valuable fluxing agents such as lime and iron, present in 
suitable form. 
The subject of the valuation of lead ores is dealt with in 



12 



LEAD ORES 

considerable detail by Hofman [4/pp. 60-66], from whose work 
much of the information given above is taken. 

The average prices of soft pig lead in the United Kingdom, 
taken from the Mining Magazine, for the years 1910 to 1919 
inclusive, are given below. Attention may be drawn to the 
rapid advance in price consequent upon the abnormal con- 
ditions brought about by the war. Owing to the acute situa- 
tion thus created the Government were obliged to assume 
control of the market and to fix a maximum price. 



Year. 


Average Price 
per longjton. 


Year. 


Average Price 
per long ton. 




I a- * 




s. d. 


I9IO 








12 19 


1915 


. 


22 l6 IO 


IQII 








13 19 3 


1916 


. 


30 19 7 


1912 








17 15 10 


1917 




30 o o 


1913 








18 6 2 


1918 


. 


30 2 8 


1914 








18 13 9 


1919 





28 3 it 



SMELTING OF LEAD ORES [4] [5] 

Although in recent years considerable developments and 
improvements have taken place in the practice of lead smelt- 
ing, particularly at large central plants, earlier methods are 
still in vogue locally, and there is a good deal of variation in 
the methods employed in different places, either in response to 
local conditions or to the character of the ore treated. Non- 
argentiferous ores, for example, lend themselves to different 
treatment from those in which the recovery of silver is of 
paramount importance. From the smelters' point of view 
lead ores are classed as sulphide ores (galena) and oxide ores 
(cerussite, anglesite, etc.), the latter being commonly called 
carbonate ores. 

Lead ore as delivered to the smelters almost invariably 
contains various impurities, so that its smelting is concerned 
not merely with the extraction of the lead from its com- 
pounds, but also with the removal so far as possible of these 
extraneous substances. The nature of the impurities has 
indeed a very considerable influence on the character of the 
smelting. Thus the presence of sulphur or arsenic necessi- 
tates a preliminary roasting, in which considerable loss of 



THEIR OCCURRENCE, CHARACTERS AND USES 13 

lead and silver may take place by volatilization. Substances 
like zinc, magnesium and aluminium impair the fusibility of 
the slag, while arsenic, antimony, zinc, copper, etc., finally 
render the lead impure, and have to be removed by subsequent 
refining. 

Since the principal ore of lead galena is a sulphide, the 
burning-off of the sulphur is a necessary preliminary to the 
reduction of the ore to metal, though oxidized ores naturally 
require no such treatment. In certain methods of smelting 
desulphurization accompanies reduction, but in the now 
usual blast furnace practice the elimination of the sulphur 
so far as possible is usually made by a preliminary roasting. 
This may be performed in the ordinary way by oxidizing 
roasting in heaps, kilns or reverberatory furnaces, or by a 
more recent method of " blast roasting," in which the ore is 
mixed with lime or gypsum and subjected to an air blast at 
a comparatively low temperature. 

Since the presence of sulphur in the ore materially increases 
the cost of smelting, it is advisable to reduce it as much as 
possible ; on the other hand, the loss by volatilization of lead, 
and of silver in the case of an argentiferous ore, entailed by 
too much roasting, makes it inadvisable to carry the process 
to completion. For this reason blast roasting, which is 
effected at a comparatively low temperature, is preferable to 
ordinary roasting, as the loss of lead and silver is very much 
reduced. Owing to the loss of metal entailed in roasting, 
some smelters, in dealing with certain classes of ore, especially 
those rich in silver, charge them raw into the furnace. 

The presence of sulphur in the blast furnace charge results 
in the formation of a matte or artificial sulphide of lead, iron 
and other base metals present. Similarly any arsenic present 
causes the formation of an artificial arsenide or speiss. 

The impurities in the ore are separated during smelting by 
combining them with other substances into a fusible silicate 
or slag which, owing to its comparatively low specific gravity, 
will float on top of the molten lead. The materials commonly 
employed for this purpose are lime, iron and silica, the com- 
position of the mixture varying with the nature of the im-. 
purities present in the ore. Ores are classed as self- fluxing, 



14 LEAD ORES 

acid or basic. The first-named contain a gangue of such 
composition as to render the addition of further fluxing 
material unnecessary. Acid ores are those requiring the addi- 
tion of a base (CaO, FeO, MnO), while to basic ores silica has 
to be added. The formation of a suitable slag is a most 
important part of the smelting process, requiring skill and 
experience, and the necessary fluxes should be readily and 
cheaply obtainable. Since the addition of fluxes adds to the 
cost of smelting by reducing the amount of ore in the charge, 
the smelters at large central establishments, dealing with the 
produce of several mines, aim at securing ores which will 
contain, upon mixing, the proper proportions of slag-forming 
substances without the addition of barren material, though 
an ideal combination is seldom attainable. A careful selec- 
tion, however, will considerably curtail the amount of flux to 
be added to the furnace charge. 

The extraction of lead from its ores is based upon two pro- 
cesses, namely : 

1. The Reaction process, in which a reaction or double 
decomposition, resulting in the formation of metallic lead 
and sulphur dioxide, takes place between lead sulphide and 
lead sulphate or oxide formed by roasting the sulphide ; and, 

2. The Reduction process, in which the liberation of lead 
from combination is effected by the reducing agency of carbon 
or of iron. 

These processes are not entirely separable in practice, and 
may be used in combination, though they are not equally 
applicable to all classes of ore. 

Lead smelting may be carried out in reverberatory fur- 
naces, in ore hearths, or in blast furnaces, the last being 
chiefly in favour at the present time. 

Reduction of the ore in reverberatory furnaces is an appli- 
cation of the reaction or double-decomposition process, the 
lead sulphate and oxide, to which the galena is partially 
converted by first roasting the charge at a temperature of 
from 500 C. to 600 C., reacting at a higher temperature, of 
about 800 C., with the unaltered lead sulphide present, with 
the liberation of metallic lead and sulphur dioxide. The first 
operation is conducted at as low a temperature as possible, in 



THEIR OCCURRENCE, CHARACTERS AND USES 15 

order to secure a maximum formation of sulphate, and the 
whole process is repeated several times, as all the lead cannot 
be extracted in one cycle. It is claimed for this method that 
the ore can be treated raw, i.e. without previous roasting, 
that few fluxes are required, and that there is little loss by 
volatilization of lead, and of silver, if present, owing to the 
low temperature at which the metal is produced. Against 
these advantages may be set the necessity for a preponderance 
of galena in the charge, which should contain not less than 
60 per cent, of lead and not more than 4 to 5 per cent, of 
silica. This method is little used at the present time. 

Smelting in ore hearths is a combined reaction and reduc- 
tion process, carbon being used as a reducing agent. Roast- 
ing and reduction proceed together. Although this method 
produces very pure lead, and has the advantages of low fuel 
consumption and quickness of starting, it is unsatisfactory 
owing to the heavy volatilization which takes place, and is 
therefore specially unsuitable for argentiferous ores. 

In blast furnace practice the principal reactions which take 
place are reduction by carbon monoxide and carbon derived 
from the fuel, and precipitation by iron, though roast reaction 
also plays some part. The treatment of complex ores can 
be more satisfactorily carried out by this than by other methods. 
The separation of the products is effected by the differences in 
their specific gravities, that of the molten lead being about 
10-5, that of the matte varying from 4-5 to 5, while that of 
a good slag should not exceed 3-6. The charge in the shaft is 
divisible into zones, according to the range of temperature 
and the reactions which occur, as follows : 

1. The zone of preparatory heating 100 to 400 C. 

2. The upper zone of reduction 400 to 700 C. 

3. The lower zone of reduction 700 to 900 C. 

4. The zone of fusion 900 to 1,200 C. 

The slag should be easily fusible at the last temperature, and 
both it and the matte should be thoroughly liquid in order 
to ensure a ready separation. For this reason the presence 
of zinc is to be avoided. 

Losses during smelting. The metal losses which occur dur- 
ing smelting naturally vary with the methods employed. In 



16 LEAD ORES 

blast furnace practice they may range from 4 to 15 per cent., 
according to the percentage of lead in the ore. Owing to a 
certain amount of unavoidable loss it is usual for smelters to 
cover themselves by only paying for 90 per cent, of the lead 
content of the ore. 

Lead fume. The gases which escape from the furnaces 
during smelting deposit in their passage through the flues a 
material known as lead fume, which consists principally of 
oxide and sulphate of lead. In order to recover as much as 
possible of the substance, and incidentally to minimize pollu- 
tion of the atmosphere with noxious gases, the flues are ex- 
tended as far as possible, in certain cases being as much as 
2 or 3 miles long, and various methods have been adopted 
for arresting the passage of the escaping gases, such as by 
suspending wire in the flue, by enlarging the flue to such an 
extent as to reduce the velocity, and by electrical means. 
Attempts have also been made to condense the gases by 
filtering them through water, screens of canvas bags, wet 
faggots, gauze or sawdust. In recent years the Cottrell 
electrostatic method of precipitating fume from furnace 
gases has been introduced into certain lead-smelting works 
with conspicuous success, the efficiency under the best condi- 
tions reaching upwards of 90 per cent. 

REFINING OF LEAD. 

During smelting, metallic impurities present in the ore are 
reduced with the lead, so that the pig lead as obtained from 
the furnaces is frequently contaminated and unsuitable for 
many of the purposes for which it is used. This necessitates 
a subsequent refining process by which the impurities are 
reduced so that only traces remain. Lead produced in 
reverberatory furnaces and ore hearths is always purer than 
that obtained when the ore is treated in the blast furnace, and 
in some cases may need no refining. The impurities commonly 
present are antimony, arsenic, bismuth, copper, iron, zinc 
and silver, and, since their presence renders the lead hard, 
their removal is known as softening. The recovery of 
silver, and of gold if present, from argentiferous lead is 



THEIR OCCURRENCE, CHARACTERS AND USES 17 

known as desilverization, and is the basis of an important 
industry. 

Lead bullion commonly contains from 95 to 98 per cent, of 
lead, while the best refined lead should contain not less than 
99-9 per cent. 

Poling of lead. This simple process is usually performed 
by the smelters, and is not, strictly speaking, a part of lead 
refining. It consists merely in agitating the molten metal so 
as to expose the impurities to the oxidizing action of the air. 
The oxides so formed remain on the surface as a dross, and 
can be repeatedly skimmed off. Formerly, poling was per- 
formed by thrusting a green pole into the lead, the gases and 
vapours given off by the wood serving to stir up the melt ; but 
in modern practice a mechanical stirring of the molten metal 
is carried out by means of steam or compressed air. 

This simple process, though far from perfect, serves to 
remove a considerable amount of impurity, and may be suffi- 
cient for the marketing of lead produced from a high-grade 
ore. In most cases, however, and especially in the case of 
argentiferous lead which has to be desilverized, a subsequent 
softening process is carried out by the refiners. 

Softening of lead. This may be accomplished by two pro- 
cesses liquation and oxidation both of which are carried out 
in reverberatory furnaces. The former consists in separat- 
ing the less fusible impurities by slowly melting the crude 
lead at a low temperature, while in the latter the metal is 
heated to a bright red heat with free access of air. In each 
case the dross which forms on the surface is continually re- 
moved to prevent the impurities redissolving into the lead. 

These methods effect a considerably higher extraction of 
the base impurities than poling, and are usually sufficient for 
the product of non- argentiferous ores, although where special 
refinement is necessary methods employed for desilverization 
are used even for such material, the small amount of silver 
recovered and the enhanced quality of the lead produced 
justifying the extra cost of treatment. Copper is extracted 
by zinc in the Parkes process, but the electrolytic process is 
the only one which offers an improved method of extracting 
such impurities as antimony, arsenic and bismuth. In any 



i8 LEAD ORES 

case, however, where appreciable quantities of these impurities 
are present a previous softening is always resorted to before 
desilverization. 

Desilverization. The refining of argentiferous lead has for 
its primary object the recovery of the precious metals, gold 
and silver ; but at the same time may have the additional 
advantage of effecting a high degree of extraction of other 
impurities, thus producing a lead of considerable purity, 
which can be sold at an enhanced price. 

The oldest method of desilverization, but one now little 
used alone, is the Cupellation process, in which the lead is 
heated in the presence of air with the formation of litharge ; 
the silver having little affinity for oxygen remains in a metallic 
state after the litharge is run off. This method is very un- 
economical, and cupellation is now used commercially only as 
an auxiliary to the Pattinson and Parkes processes described 
below. The Parkes process, which makes use of zinc, has of 
recent years almost entirely replaced the Pattinson, though 
sometimes the two are run in conjunction, the latter being 
used to bring the lead to a tolerable richness of about 40 to 
60 oz. of silver to the ton. 

The Pattinson process is based upon the fact that when 
low-grade lead bullion is melted and then cooled to its freezing- 
point, the crystals of lead which separate are much poorer in 
silver than the original material. By repeated meltings and 
crystallizations it is possible to obtain a quantity of marketable 
lead low in silver, and the remaining enriched material cari 
then be cupelled for the recovery of the precious metal. More- 
over, the repeated meltings necessary tend to eliminate the 
other impurities by dressing, and thus to enhance the quality 
of the market lead. In this process gold separates with the 
silver, and bismuth shows a similar behaviour, though the 
separation is not so complete. For most purposes, however, 
the removal of bismuth in this way is sufficient. 

The Luce-Rozan process is a modification of the Pattinson 
method, wherein steam is used to agitate the melt during 
crystallization, causing a better and more regular separation 
of the crystals. It also poles the lead and thus produces a 
purer product. 



THEIR OCCURRENCE, CHARACTERS AND USES 19 

Parkes's process makes use of the fact that gold, silver and 
copper have a greater affinity for zinc than for lead, so that 
the addition of zinc in proper quantity to the mixture robs the 
lead of these metals, forming gold-zinc, silver-zinc and 
copper-zinc alloys. These alloys, being lighter than lead, and 
having higher melting-points, separate on cooling, and form 
a scum which can be skimmed off and from which the zinc 
can be removed by distillation. The quantity of zinc required 
depends upon the amount of silver contained in the lead, and 
varies between i and 2 '5 per cent. For this process the lead, 
before being desilverized, is softened by liquation or oxidation 
in a softening furnace. 

The Belts process, which is the only really successful method 
of electrolytic refining, is carried out with an electrolyte of 
lead fluo-silicate acidified with hydro- fluosilicic acid, and the 
lead to be refined is cast into sheets for use as anodes and 
cathodes. During the decomposition of the anode lead, and 
its redeposition on the cathode, the impurities remain behind 
in the anode mud, which is collected and refined for their 
recovery. This process has the great advantage of not only 
recovering the precious metals, but also of effecting an im- 
proved extraction of the base impurities, especially bismuth. 

MARKETING OF LEAD 

Commercial lead naturally varies somewhat in composi- 
tion according to the nature of the original ore and the methods 
adopted for smelting and refining it, but has usually a high 
degree of purity, and contains only traces of other metals. 

The table on the next page gives the percentages of im- 
purities shown by analyses from various sources (quoted from 
Thorpes's Dictionary of Chemistry and Hofman's Metallurgy 
of Lead). 

Lead is marketed in three grades : (a) desilverized, (b) soft, 
(c) antimonial or hard. The second term is applied to the 
product of a non- argentiferous ore which has been refined in 
the ordinary way, and is less pure than desilverized lead. It 
may be ordinary or chemical hard, the latter containing a 
rather higher percentage of antimony and copper, which, 



20 



LEAD ORES 



ts 

i 

t-J 

*-* 



1 



O 



s 







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H O t"* fO ro O 






B 


000 o o 
o o o o o 


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0900 


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O O O O O Co CO 








o o o o o . j^ 


















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"OOrtOrt dO 


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9 P ? 9 43. 


p 






fo <*- 1000 

















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o o o o o 


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00000 


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.8 


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11 



THEIR OCCURRENCE, CHARACTERS AND USES 21 

however, increase its resistance to acids, and make it especially 
useful for certain purposes in chemical industry. 

Antimonial lead is an alloy of lead with about 15 to 30 per 
cent, of antimony, which is produced as a by-product in 
desilverizing. Owing to the irregular composition of the 
material so produced, it is not, however, considered so satis- 
factory by the users of alloys as when made directly by 
mixing lead and antimony in the desired proportions. 

The purest grade of lead, described as corroding, is in great 
demand for the manufacture of whitelead. It may be pro- 
duced from very pure ores by ordinary refining, but is usually 
desilverized lead. Lead refined electrolytically by the Betts 
process is of this nature. 

PROPERTIES OF LEAD 

Lead is a bluish-grey metal having a good lustre on freshly- 
fractured surfaces, though it soon tarnishes on exposure to 
the atmosphere. When pure it is sufficiently soft to be 
scratched by the finger-nail, and makes a grey-black streak 
when rubbed on paper. It is very malleable, but not suffi- 
ciently ductile to be drawn into fine wire. Its tenacity is the 
least among the common metals. It may be easily rolled into 
sheets or extruded through dies to form piping. 

Lead is the heaviest of the base metals, having a specific 
gravity of 11-37 when solid and of 10-65 when molten (Reich). 
Its atomic weight is 207-1. It melts at 327-4 C. and boils at 
1,525 C. It does not crystallize readily, but when cooled 
slowly forms small imperfect octahedrons. 

On exposure of lead to moist air at ordinary temperatures 
the suboxide (Pb 2 0) is formed ; when melted in contact with 
air it is converted to monoxide (PbO), the yellow amorphous 
massicot being first formed at a low red heat, while, at a 
higher temperature, a bright red heat, this undergoes a 
molecular change with conversion to crystalline litharge. 
Steady heating at a temperature of from 300 to 500 C. con- 
verts litharge (PbO) into red lead (Pb 8 4 ), but this is dis- 
sociated at 550 C. At high temperatures the metal combines 
with silica and is therefore undesirable in furnaces with 



22 LEAD ORES 

siliceous linings. Lead has a great affinity for the noble 
metals. 

Impurities of antimony, arsenic, zinc, magnesium, copper 
and silver render the metal harder, while tin and bismuth 
increase its fusibility. The hardness may be increased also 
by repeated meltings. Antimony, bismuth and copper are 
said to protect it against the action of sulphuric acid at 
low temperatures ; zinc, on the other hand, renders it more 
susceptible. 

UTILIZATION OF LEAD [5] 

The extreme malleability of lead makes it possible to use 
this metal for many purposes for which other base metals are 
unsuitable ; thus it is extensively used as sheeting and piping. 
Sheet lead is made by first casting the metal into plates several 
inches thick, which are then rolled in a mill to the required 
thickness. It is largely used as a lining for sinks, acid cham- 
bers, vats, etc. ; as a roofing material, though now not so 
extensively as formerly ; as plates for electric storage bat- 
teries ; and as a covering for electric cables. Lead piping, 
prepared by extruding the metal by hydraulic pressure through 
a die, is used extensively for conveying drinking-water and 
gas in dwelling houses, and is also employed in chemical works. 
For these purposes the lead is usually hardened by the addi- 
tion of tin and antimony. 

The high specific gravity and fusibility of lead render it 
suitable for the manufacture of bullets and shot, for which 
purpose it is usual to harden it by the addition of arsenic, 
antimony or tin, which increases the penetrating power and 
prevents the shot sticking together when the explosion occurs. 

Lead enters into the composition of a large number of 
alloys, which are considered in the next section (p. 23). 

Litharge, or lead monoxide, is largely used in the manu- 
facture of the chrome pigments, as a flux, in the rubber in- 
dustry, and in glass-making. It is commonly prepared by 
heating lead in a low reverberatory furnace, with free access 
of air, at a bright red heat. Appreciable quantities are re- 
covered in the metallurgy of silver. The commercial article 
frequently contains such impurities as iron, copper, silver 



e 



THEIR OCCURRENCE, CHARACTERS AND USES 23 

and metallic lead ; and if care has not been exercised in regu- 
lating the heat during its manufacture, some red lead is usually 
present. Various qualities of litharge are known commercially 
by such names as colour-makers' oxide, enamellers' oxide, 
glass-makers' oxide, potters' oxide, rubber-makers' oxide and 
varnish-makers' oxide. 

Various lead salts are used for industrial purposes. The 
nitrate is employed in the calico dyeing and printing trades, 
and for decolorizing sugar solutions ; the arsenate is largely 
used as an insecticide for the protection of fruit trees ; while 
the acetate and carbonate are used for medicinal purposes. 

One of the most important applications of lead is in the 
manufacture of pigments, especially whitelead. Other lead 
pigments are red lead, orange lead and the lead chromes. 
Red lead, in addition to its employment as a pigment, is also 
used by plumbers as a cement for pipe joints ; in the manu- 
facture of glass ; and in the match-making trade. Owing to 
its anti- corrosive properties it is very extensively used as a 
coating for the protection of structural steel. 

It is estimated that over 40 per cent, of the lead produced 
in the United States of America is converted into whitelead, 
red lead or litharge. The manufacture of lead pigments is 
dealt with in a later section (pp. 26-32). 

Lead Alloys 

The table on page 24 gives the percentages of metals con- 
tained in various industrial lead alloys. 

It will be noticed from this table that tin plays a promi- 
nent part in lead alloys, the effect of this metal being to 
harden the lead without increasing its brittleness or altering 
\its malleability. The two metals will alloy in all propor- 
tions; the strongest alloy in tension is composed of 27-5 
per cent, of lead and 72-5 per cent, of tin, while the most 
ductile contains 60 per cent, of lead and 40 per cent, of tin. 
Alloys with an almost equal percentage of the two metals are 
the best for ordinary use. Lead-tin alloys are principally 
used for solder, pewter, organ pipes and toys. 

Several alloys are made with antimony. This metal im- 
3 



I 



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LEAD ORES 



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THEIR OCCURRENCE, CHARACTERS AND USES 25 

parts considerable hardness to lead, but renders it brittle, and 
where the content is over 24 per cent., the addition of a third 
metal, usually tin, to counteract this effect is advisable. 
Battery plates (94 per cent, lead and 6 per cent, antimony), 
engraving plates (60 per cent, lead and 40 per cent antimony, 
with usually a little tin), type metal (82 per cent, lead, 
15 per cent, antimony and 3 per cent, tin) and bullets (with 
6 per cent, antimony plus small quantities of arsenic) are 
examples of the application of these alloys. Lead-antimony- 
tin alloys usually go by the name of white metal, or anti- 
friction metal. 

Fusible alloys are composed of lead, tin, cadmium and 
bismuth, in various proportions. 

The presence of zinc renders lead too hard for rolling, and 
also makes it liable to corrosion by acids. Copper, on the 
other hand, increases its resistance. 

The hardening effects of certain metals upon lead have 
been investigated by Ludwick (Zeits. anorg. Chem., vol. 94 
(1916), p. 161), by means of the Brinell method, and some 
of his results are shown in the annexed table (quoted from 
Hofman) : 



Added Metal. 


Percentage. 


Quenched. 


Annealed. 


Brinell No. 


Brinell No 


For 2 to 3 on. 
at Deg. C. 


Antimony . . -| 


I 
2 

I 


7-6- 8-2 
9-8- 9-9 
10-7-10-9 

I3-6-I3-9 
16-8-17-3 


6-8- 7-1 

9-5- 9-7 
15-1-16-5 
14-0-14-3 
15-8-16-1 


230 


Tin . 


-5 
i 

2 

8 


6-0- 6-4 
6-8- 6-9 
8-0- 8-1 
10-6-10-9 


6-0- 6-4 
6-6- 7-2 

7-4- 7-9 
n-3-11-4 


270 
230 




o-5 


9-1- 9-2 


8-9- 9-4 






i 

2 

8 


9-5-10-2 

II-6-I2-2 
16-7-19-8 


9-7-10-1 
12-6-12-7 
14-2-14-5 


270 
2 2O 


Magnesium . -j 


0-5 
i 

2 


I3-5-I5-5 
I7-9-I9-6 
22-3-22-6 


13-8-13-9 
16-3-16-4 
19-8-20-9 


22O 



26 LEAD ORES 

Lead Pigments [6] [7] 

The lead pigment of chief commercial use is whitelead, 
while next in importance is red lead. Others are the various 
lead chromes, orange lead and several of minor importance. 

Although the lead pigments have a high density, and pos- 
sess considerable staining powers, their ready susceptibility 
to chemical impurities in the air precludes them from ranking 
as good colours. The presence of soluble sulphides soon 
causes them to blacken. The lead chromes especially are 
notorious for their instability. Another great drawback to 
the use of lead pigments is the danger of poisoning incurred. 

WHITELEAD.- This pigment, which is of great antiquity, hav- 
ing been used by the ancients as a cosmetic, is now invariably 
prepared artificially, and not from the natural lead carbonate, 
cerussite. The manufactured article is a basic lead carbonate 
represented by the formula 2PbC0 3 ,Pb(OH) 2 , which corre- 
sponds to about 70 per cent, of carbonate and 30 per cent, of 
hydrate. Although the different processes of manufacture 
may result in slight differences of composition, the ratio of 
carbonate to hydrate should vary but little, since any appre- 
ciable alteration in the above proportions seriously affects the 
quality of the pigment. The percentage composition should 
approximate to : 

Plumbic oxide PbO .... 86-32 
Carbon dioxide COa .... 11-36 
Water H a O . . . 2-32 

100-00 per cent. 

Whitelead experiences serious commercial competition from 
zinc oxide and barytes. The latter material, moreover, is 
frequently used as an adulterant of whitelead, and considerably 
lessens the cost of production, though it is claimed that the 
addition of a small quantity of barytes has a beneficial 
effect in rendering whitelead less susceptible to the ravages 
of sulphuretted hydrogen and other soluble sulphides. Its 
presence may be detected with the aid of dilute nitric acid, 
which will completely dissolve pure whitelead, but is without 
action on barium sulphate. Another form of adulteration is 



THEIR OCCURRENCE, CHARACTERS AND USES 27 

the addition of ultramarine or indigo to mask the yellow tinge 
in some whiteleads. 

For paint-making, whitelead is ground with linseed oil, the 
amount requisite varying to some extent with the age of the 
pigment and its mode of manufacture, but on an average 
7 per cent, of oil will be required. Whitelead considerably 
improves with age before grinding. 

Various other lead compounds, such as the basic sulphate, 
used either alone or as a mixture with zinc oxide under the 
name of leaded- zinc- white, have been introduced, but they do 
not possess the body of whitelead, and have met with no great 
measure of success, chiefly because hitherto they have not 
shown the constancy of composition which is a feature of the 
long- established brands of whitelead. Sublimed whitelead, 
which consists principally of basic sulphate, is, however, meet- 
ing with an increased demand, and although its colour at first 
is not equal to that of ordinary whitelead, this improves with 
age, while that of the latter, of course, deteriorates. Owing to 
its fineness of grain it finds favour chiefly for mixing with other 
pigments. 

Commercial Preparation of Whitelead. Several methods are 
in vogue for the manufacture of whitelead, most of which are 
based on the old Dutch process of converting lead to basic 
lead acetate, and treating that with carbon dioxide. The means 
adopted to secure the reactions differ considerably, however, 
and in the newer or so-called quick processes are directed to- 
wards a speeding-up of the reactions. The principal methods, 
known as the old Dutch, German, Carter, Matheson and Mild 
processes, are described below. 

In England practically all the whitelead is made by the 
old Dutch method, though the German Chamber process is 
used in a few cases. London and Newcastle are the principal 
places of manufacture, and plants are situated also in Bristol, 
Sheffield, Chester and Glasgow. English brands of whitelead 
show great care in manufacture, and are regarded as very pure 
and of good colour. 

In Germany and adjoining countries the Chamber process 
finds favour, but in France the old Dutch method is still 
generally used. 



28 LEAD ORES 

In the United States there are large plants operating the 
Carter, Matheson and Mild processes, but the Dutch method 
is also employed with modifications. 

There is a great tendency towards conservatism among 
whitelead manufacturers, especially in Europe, so that the old 
Dutch method is still chiefly in use, though it is claimed that 
the newer processes produce a purer product and are more 
economical. The reasons for this attitude are apparently that 
long-standing practice has resulted in an intimate knowledge 
and control of the details of the process, thus enabling uni- 
formity of quality to be maintained, and that established 
brands of whitelead have a ready and secure market against 
which it is difficult to compete. In the United States, how- 
ever, the newer processes have made considerable headway, 
and are operated on a large scale. 

Old Dutch process. This method, which is the oldest, is 
still responsible for a very large amount of the whitelead 
made. Modern practice differs but little from that of former 
days. 

For the manufacture of whitelead on the basis of the old 
Dutch process it is essential that the lead used be of high 
grade, and in the best brands of corroding lead the impurities 
do not exceed o-oi per cent. 

Conversion to acetate is effected by means of vinegar or 
acetic acid, and subsequent carbonation through the agency 
of horse-manure and spent tan-bark in a state of fermentation. 
The lead to be treated is cast * into thin gratings or buckles, 
so as to expose as large a surface as possible to corrosion, and 
is suspended over the vinegar or acetic acid in earthenware 
jars, which are arranged on beds of manure and tan. A 
number of beds, usually ten or twelve, separated by layers of 
boards, are built one above the other, constituting a stack, 
and are left thus for from three to four months. The fermenta- 
tion of the tan-bark not only liberates carbon dioxide, but 
also raises the temperature sufficiently to vaporize the acid. 
The product removed from the stack at the expiration of the 
treatment is crushed and screened to separate the whitelead 

* It is essential that cast and not rolled lead be used, since the latter, owing 
to its hardness, would corrode only with difficulty. 



THEIR OCCURRENCE, CHARACTERS AND USES 29 

from the cores of unaltered metallic lead. The former is 
ground in water, and afterwards recovered in settling tanks 
and dried. 

The successful running of this process depends upon the 
correct tempering of the tan-bark, which should not be too 
moist or allowed to overheat. 

The German Chamber process. The essential features which 
distinguish this method from the old Dutch process are the 
vaporizing of the acid and the introduction of this and 
carbon dioxide, produced in coke furnaces, into the stack 
through perforated pipes, so that the actions are under the 
direct control of the operator. Corrosion is carried out in 
large closed chambers, in which strips of lead are suspended 
from racks. It is imperative for the success of this method 
that the acid be introduced in correct amount and strength, 
and that a proper temperature be maintained. 

The Carter -process. In this and the next described methods, 
the principles of which are the same as those of the Dutch 
process, corrosion is accelerated by reducing the lead before 
treatment to small particles, and by assisting the action with 
mechanical devices. Moreover, as in the German process, the 
use of carbon dioxide gas, and the elimination of the decom- 
posing organic matter employed in the old Dutch process, 
ensures the absence of sulphuretted hydrogen with its 
attendant blackening effect, and affords, therefore, a product 
of great whiteness. It is claimed, further, that the percentage 
of converted lead is from 85 to 90 per cent., as against about 
70 per cent, in the old Dutch method. 

In the Carter process the lead for treatment is submitted 
when molten to a jet of steam at high pressure, which breaks 
it up into a coarse granular powder. This powder is treated 
in slowly-revolving, long, wooden drums, in which it is sprayed 
at intervals with dilute acetic acid, and subjected to a current 
of gas containing 10 per cent, of carbon dioxide. The revolu- 
tion of the drums causes greater exposure of the material 
to corrosion, at the same time preventing by abrasion the 
formation of crusts on the individual grains. Each charge 
takes roughly twelve days to treat. For the success of this 
process the lead must not be granulated too fine, and care must 



30 LEAD ORES 

be taken not to add too much water or acid, as otherwise the 
mass becomes pasty and the reactions are retarded. 

The Matheson process. In this process also, advantage is 
taken of the more rapid corrosion produced by reducing the 
lead to small dimensions. For this purpose the molten metal 
is poured into water, and induced to take a spongy form. It 
is then converted to acetate in large tanks by contact with 
acetic acid in the presence of steam and air, being subse- 
quently changed to carbonate by the action of carbon dioxide 
obtained from coke furnaces. Washing and drying complete 
the process, the removal of excess water being accomplished 
by means of filter presses. 

Matheson whitelead is remarkably free from metallic lead, 
but usually contains basic acetate of lead. Although claimed 
as purer and whiter than that produced by the old Dutch 
method, it requires more oil for paint-making. 

The Mild or Rowley process. This process, which produces 
the purest whitelead, is also the cheapest and simplest, involv- 
ing the use of neither acids nor alkalies, nor of any reagents 
other than carbon dioxide, air and water. The resulting 
product is claimed to have a whiteness and density not ex- 
ceeded by that of any other make of whitelead. The process 
is based upon the atomization or reduction of the lead into 
extremely small particles, which is effected by subjecting it, 
while molten, to the action of high-pressure superheated 
steam. The particles so formed have a thin coating of lead 
suboxide, which is very susceptible to further oxidation, and 
by mechanical agitation of the material with air and water 
in oxidizing boxes, basic hydroxides are formed. After 
separation from any metallic lead remaining, the oxidized 
product is treated with flue gas, containing about 18 per cent, 
of carbon dioxide, in carbonating tanks. The two processes 
take about thirty-six hours each, and if carefully conducted 
result in a product of practically theoretical composition. The 
absence of impurities renders any further treatment, other 
than drying, unnecessary after removal of the material from 
the carbonators ; and owing to the small size of the particles 
the product easily crumbles to a fine powder. The whole 
process is simple and easily controlled, and possesses the 



THEIR OCCURRENCE, CHARACTERS AND USES 31 

great advantage of not requiring the highly refined grade of 
lead used in the Dutch process, any good ordinary grade 
sufficing. Mild process whitelead is said to be whiter, purer, 
finer and of a more uniform grain than that produced by the 
Dutch process. 

RED LEAD. This pigment has the same composition as 
natural red lead or minium (Pb 3 O 4 ), though that mineral is 
never found in sufficient quantities to be of commercial appli- 
cation. It is of a beautiful scarlet-red colour, but owing to 
its liability to discoloration, and its tendency to dry quickly, 
red lead is little used as an oil paint, and is quite inadmissible 
as a water-colour. Its anti- corrosive properties, however, 
make it peculiarly desirable as a protective covering for steel 
work of all kinds. Owing to its great opacity red lead readily 
lends itself to adulteration, the materials commonly employed 
for that purpose being barytes and ground glass. The paler 
and more orange- tinted varieties contain an excess of lead 
protoxide. 

In the usual manufacture of red lead from lead two opera- 
tions are involved, the metal in the first place being converted 
into massicot, or yellow lead monoxide. In this operation the 
lead is heated in a dressing oven, or low reverberatory furnace, 
with free access of air, the temperature being carefully regu- 
lated and maintained slightly above the melting-point of 
lead, i.e. at about 340 C., as otherwise the oxide formed under- 
goes a molecular change with conversion to litharge. On the 
completion of oxidation the charge is allowed to cool, and is 
then ground and levigated to free it from metallic lead. 

The second operation, known as colouring, is performed in 
a similar manner, but at a lower temperature. As the oxide 
while hot has a deep purplish colour, only becoming bright 
red when cold, samples must be withdrawn from the furnace 
from time to time in order to test the coloration. When 
oxidation is complete the material is reground, levigated and 
dried, as before. The successful operation of this process is 
closely dependent upon a careful control of the temperature 
during oxidation, as upon this factor depends the molecular 
state of the oxide and its consequent brightness and depth of 
colour. 



32 LEAD ORES 

The foregoing method of manufacturing red lead is prac- 
tically universal, though the Nitrate process, which involves 
the use of sodium nitrate as an oxidizing agent, has met with 
considerable success, owing to the value of the by-product, 
nitrite of soda, produced. 

ORANGE LEAD. This is a material of similar composition 
to red lead, but of different colour, being of a bright orange 
shade. It is produced by the roasting of whitelead, the 
material used for this purpose being frequently the waste from 
the washing and settling tanks. 

LEAD CHROMES. The pigment known as chrome yellow is 
normally a neutral lead chromate, though the darker, orange 
and reddish- orange varieties contain also basic lead chromate. 
The pale-coloured chrome yellows (canary and lemon chromes) 
have varying percentages of lead sulphate. Chrome yellow is 
usually made by the reaction of a soluble lead salt, such as the 
acetate or nitrate, with chromate or bichromate of potassium 
or sodium. Although lead nitrate produces a richer and 
stronger-coloured pigment than the acetate, the lower cost of 
the latter makes it chiefly in favour among colour manufac- 
turers, who prepare it from litharge. For this purpose the 
litharge should be free from red lead, since this is insoluble in 
acetic acid. 

The various shades of chrome pigments are commonly de- 
scribed as canary yellow, lemon yellow, chrome yellow, chrome 
orange and American vermilion (Chinese scarlet, Persian red, 
etc.), the last named being of a scarlet red colour. Chrome 
greens are mixtures of chrome yellow and various blue 
pigments. 

Like all lead pigments the chromes are distinctly unstable, 
and readily darken in the presence of soluble sulphides. They 
have also a tendency to reduction by organic matter. 

STATISTICS OF PRODUCTION AND CONSUMPTION OF LEAD 

Useful particulars regarding the production and consump- 
tion of lead were given for many years previous to the war in 
the annual volume of Comparative Statistics published by the 
Metallgesellschaft at Frankfort-on-Main, but recent issues 



THEIR OCCURRENCE, CHARACTERS AND USES 33 

of this publication have not been available in this country. 
The Mineral Industry, published annually in New York, con- 
tains much valuable information. For the United States 
reference may be made to the very complete publication 
issued annually by the United States Geological Survey under 
the title of Mineral Resources of the United States. 

The statistical tables in this monograph have been com- 
piled from various sources by the staff of the Imperial Insti- 
tute, and give in a ready form for reference a mass of in- 
formation regarding the production and consumption of lead 
in the various countries concerned.* Wherever possible the 
period covered is from 1910 to 1920 inclusive, but figures for 
the later dates are, in many cases, at present unobtainable, 
and the tables are therefore incomplete. 

It is hoped that these omissions may be rectified in a 
subsequent edition of this monograph. 

The largest producer of lead ore in the world is the United 
States of America. Next in importance, in the years pre- 
ceding the war, were Australia, Germany, Spain and Mexico. 
The output of Mexico declined considerably, however, during 
the revolution, but has recently been restored. The present 
position of Germany is naturally uncertain, but in any case 
her production must have diminished considerably, since the 
Silesian deposits, from which her main output was derived, 
were practically closed down after the armistice, and their 
future ownership is still a matter of doubt. 

The productions of the remaining European countries, in- 
cluding the United Kingdom, are much smaller, and in many 
cases are insufficient to meet the domestic demands, which 
have therefore to be partly satisfied by imports. 

The world's production of dressed lead ore by countries 
from 1910 to 1918 is shown, as far as information is obtain- 
able, in Table I (page 35), whilst the world's production of 
metallic lead, for the same period, is shown in Table II (p. 38). 
In the latter the quantities shown include, in most cases, lead 
derived from both domestic and imported ores, though there 
are certain exceptions, as, for example, the United Kingdom 
and the United States. 

* Unless otherwise stated, the figures given are from official sources. 



34 



LEAD ORES 



An account of the distribution and production of lead was 
given by Ingalls in the Mineral Industry for 1893 [2]. Dia- 
gram I (p. 36) and Diagram II (p. 37) show graphically the 
outputs of metallic lead of the larger producing and the prin- 
cipal smaller producing countries of the world respectively 
for the period 1910-1918. 

The exports of lead from the chief producing countries are 
shown in Table III, whilst the imports of lead and of dressed 
lead ore into the chief countries of consumption are shown in 
Tables IV and V respectively (p. 39). 

According to John E. Orchard, of the United States Bureau 
of Mines, a recent total production of 1,371,000 short tons 
of pig lead was financially and politically controlled by 
different countries as shown below [3] : 

















Financial eontrol 


Political control 
















(Commercial) . 
Per cent. 


(Geographical). 
Per cent. 
















of total. 


of total. 


United States 














49 


45 


British Empire 














I? 


13 


France 














13 


2 


Germany 














15 


14 


Spain . 
















II 


Austria-Hungary 

















2 


All others . 














6 


13 
















IOO 


IOO 






THEIR OCCURRENCE, CHARACTERS AND USES 35 



World's Production of Dressed Lead Ore 
In metric tons (2,204 ^-) 


i* 


S * S 
*t- co r* co ob (-* r>.o O 

5 I ? T 1 ^ ^11 * 1 1 M ^ ^ 1 
v 1 t^ct Qt o HI|| ii "">*' 

M C* u") t-*> HI M wrn 


1 


1 Mines and Quarries Report. ' Records of the Geol. Surv. India ore only, slags not included. 
Rhodesia and Union of S. Africa only. 
* Mineral Production of Canada, Mines Department ores shipped, 1910-11 estimated (lead production x 3-63). 
6 New South Wales ; Queensland ; S. Australia ; W. Australia and Tasmania. New South Wales only. 
7 Austria only. Includes Algeria and Tunis. Can. Weekly Bull., Nov. 15, 1920, 23. p. 1457. 
10 Tunis not included. u From Mineral Industry. 1J From Chinese Trade Returns 1919. 
11 Exports. u Estimated at double the production of lead for the year. 


00 

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500 



400 



350 



300 



350 



150 



Ot O* O> Ch 






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United States. 



Gerinauy 



Spain. 

Australia. 



Mexico. 



DIAGRAM'!. SHOWING ANNUAL PRODUCTIONS OF LEAD OF THE LARGER 
PRODUCING COUNTRIES (THOUSANDS OF METRIC TONS) 

Note. For some additional information see Table II, p. 38. 



6o 



Belgium. 




France. 



United Kingdom. 

India. 



1 [ Peru. 

Austria-Hungary. 

i ~* South Africa. 

DIAGRAM II. SHOWING ANNUAL PRODUCTIONS OF LEAD OF THE SMALLER 
PRODUCING COUNTRIES (THOUSANDS OF METRIC TONS) 

Note. For some additional information see Table II. p. 38. 



37 



38 



LEAD ORES 



"-) 7 



Oi 


in o^o o 

TJ- rj- M rO 

f ui Oj I i u-> 
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^ 1 




1 From Records of the Geol Surv., India ; includes lead from old slags. 
'Rhodesia only for 1910, Rhodesia and Union of S. Africa 1911-16, latter from W. Versfeld, The Base Metal Resources of the 
Union of S. Africa, 1919, p. 46. 
From Canada Department of Mines. < Exports. 6 Hungary only. 
Estimated at half the production of lead ore for the year. 
7 From Mining and Scientific Press, February 7, 1920 (" Prely. Rept. U.S. Geol. Surv."). 


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THEIR OCCURRENCE, CHARACTERS AND USES 39 



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II 



CHAPTER II 
SOURCES OF SUPPLY OF LEAD ORES 

(a) BRITISH EMPIRE 

As a producer of lead ore for some years past the British 
Empire has ranked next to the United States a position 
entirely due to the large output contributed by Australia. 
Failing this, the production would have fallen far short of 
that of Germany. 

The deposits of the United Kingdom, at one time the 
largest producer in the Empire, have been exploited over a 
very long period, and the output is now considerably less than 
formerly, though doubtless it could be materially increased 
by further exploration. A large number of the mines, how- 
ever, are abandoned, and many must be in an exhausted or 
impoverished state, so that their future possibilities are a 
matter of considerable uncertainty. It is not to the United 
Kingdom, however, that we must look for the large tonnages 
of the future. As a whole the Empire undoubtedly contains 
very large resources, many of which are as yet unknown or 
imperfectly developed. The potentialities of countries like 
Canada, Australia, British portions of Africa and India must 
be very considerable, and many important deposits are already 
known and worked in these countries. Attention may be 
drawn to the position of Burma with its large reserves and 
increasing production. The supply of lead ore within the 
Empire could certainly be relied upon to meet the demand. 

EUROPE 

UNITED KINGDOM 

Lead ores are widely distributed in the United Kingdom, 
but the mining industry has lost its former importance. Lead 

40 



UNITED KINGDOM 41 

mining was most prosperous about the middle of the last 
century, the maximum annual output of 101,997 tons of 
dressed ore being reached in 1856, when 353 mines were 
operating. Since 1870 the output, though subject to annual 
fluctuation, has shown a general decline, and in 1914 the total 
production was only 26,013 tons from about sixty mines. 

Interesting information regarding the production of lead 
ore in the United Kingdom is given in the report of the Con- 
troller of the Department for the Development of Mineral 
Resources in the United Kingdom, issued by the Ministry of 
Munitions in 1918 [8/p. 15]. According to this authority 
" the total output of dressed lead ore from the United King- 
dom for sixty years, dating from 1856 to 1915 inclusive, has 
amounted to 3,498,279 tons, from which 2,590,845 tons of 
metal have been obtained, with a value of 46,412,246, to 
which has to be added the value of silver recovered, which was 
5.023,350, making a grand total of 5M35.59 6 - 

" This production has been derived from various parts of 
the United Kingdom in proportions as follows : 



England . 
Wales . 
Scotland 
Ireland . 
Isle of Man 



Tons lead metal. 
1.505,819 

7 2 5.055 

148,617 

36,211 

I75.M3 

2,590,845 " 



The average metal content in the dressed ore has been about 
75 per cent. 

Since 1914 the abnormal conditions created by the war 
have had a serious effect upon the mining industry, and diffi- 
culties connected with shortage of labour and machinery have 
considerably curtailed outputs. On the other hand, the 
demand created for home ore supplies and the increase in the 
price of the metal have had the effect of directing attention 
to many derelict properties which, under normal conditions, 
were considered worthless, though the extensive nature of the 
operations necessary in most cases to bring these properties 



42 SOURCES OF SUPPLY OF LEAD ORES 

again to a productive state has prevented any immediate 
results. Moreover, it is very doubtful whether, so far as lead 
is concerned, any considerable tonnages are available from 
many of these sources, for although in some instances increased 
mining costs combined with a fall in the value of the metal 
were the main factors in causing abandonment, it cannot be 
doubted that in others the root cause is to be found in the 
exhaustion or impoverishment of the deposits. With respect 
to financial burdens, reference may be made to the heavy 
pumping charges and to the difficulties of transport with 
which many mines had to contend. With regard to the 
former, attention is now being directed to the driving of deep 
adits in order to effect efficient and cheaper drainage, and 
such schemes are under construction or consideration in 
Shropshire, Flintshire and Leadhills. The latter difficulty 
may be met by means of aerial ropeways, as has been done in 
Shropshire. 

The table on page 43, taken from the Home Office Re- 
ports [9], gives the amounts, in long tons, of dressed ore 
recorded from each of the producing counties from 1915 
to 1919 inclusive. It is interesting to compare this table 
with that for the year 1856 given in the report referred to 
above [8/p. 15]. 

The lead ores of the United Kingdom occur in various 
formations ranging from the Pre- Cambrian to the Triassic, but 
the commercially important deposits are mostly found in 
rocks of Palaeozoic age. They fall naturally into two groups, 
namely, veins in the older Palaeozoic rocks, and cavity- 
fillings and metasomatic replacements in the Carboniferous 
Limestone and associated rocks. The former occur in Corn- 
wall and Devon, Wales, Shropshire, the Lake District, Isle 
of Man, the Leadhills and Wicklow ; while the latter are 
found over an extensive area in the north of England, in 
Derbyshire, Flintshire and Denbighshire, and the Mendip Hills. 

Of the English counties, Durham has always been the chief 
producer ; in Scotland, the Leadhills district has been respon- 
sible for about 95 per cent, of the entire output of that country ; 
while in Ireland the main production has come from the 
mines in County Wicklow. 



UNITED KINGDOM 



43 



Production of Dressed Lead Ore in United Kingdom, in long 
tons, 1915-19 





1913. 


1916. 


1917. 


1918. 


1919. 


England t 












Cheshire . 











20 





Cornwall 


9 


15 


7 


12 


I 


Cumberland . 


897 


839 


720-5 


706 


1.405 


Derbyshire 


3.944 


3,232 


3,585 


2,699 


2,930 


Durham 


4.123 


4.045 


3.840 


3.369 


2,681 


Northumber- 












land . 


648 


589 


429 


909 


429 


Shropshire 


77 


32 


15 


27 


12 


Westmorland 


647 


735 


683 


846 


640 


Yorkshire 


14 


57 


42-5 


17 


8 


Wales : 












Cardigan 


1,802 


1,163 


896 


553 


39i 


Carmarthen . 


i? 


26 


47 


8 




Carnarvon 


128 


184 


141 


129 


51 


Denbigh 





3 


9 


19 


5 


Flint . 


2,721 


1,703 


824 


1,54 


1,386 


Montgomery . 


410 


365 


85 


38 


16 


Scotland : 












Dumfries 


3.135 


2,333 


2,056 


I.7I5 


i, 860 


Lanark . 


1,943 


1,577 


i,773 


i,952 


1,896 


Ireland : 












Armagh . 





i 











Sligo 








4 


4 


4 


Wicklow 










15 


20 


Isle of Man 


299 


208 


165 


206 


129 


Totals (long tons) 


20.744 


17,107 


15.322 


14,784 


13.868 


(metric tons) 


21,082 


17,386 


15,572 


15,025 


M.095 



The silver content of the ore shows considerable local varia- 
tion, the average being about 6 oz. to the ton of concen- 
trate. By far the greatest amount has been yielded by 
Cornish ores, and important quantities have been recovered 
also from the ores of Devonshire, the Lake District, Isle of 
Man, Cardiganshire, North Wales and Derbyshire. In Shrop- 
shire and Yorkshire, on the other hand, the galena is prac- 
tically non-argentiferous. 

The accompanying table shows the quantities of silver 
contained in the ores raised in 1918 [9] : 



44 



SOURCES OF SUPPLY OF LEAD ORES 



Table showing quantities of Silver obtainable from Lead Ore 
produced in United Kingdom during 1918 



Dressed lead ore 
(in long tons). 



Amount of silver 
content (in oz.). 



England : 

Cheshire 20 

Cornwall . . 12 

Cumberland ..... 706 

Derbyshire 2,699 

Durham 3.3 6 9 

Northumberland . . 99 

Shropshire . 27 

Westmorland . . . 846 

Yorkshire ...... 17 

Wales t 

Cardigan 553 

Carmarthen ..... 

Carnarvon 129 

Denbigh ...... 19 

Flint 1,54 

Montgomery ... . 38 

Scotland, : 

Dumfries ... . i,7 I 5 

Lanark 1,952 

Ireland : 

Sligo .... . 4 

Wicklow 15 

Isle of Man 206 

Totals .... 14.784 



5.975 

15,129 
3.944 

8,319 
63 



5.134 
36 

1,65 
48 

10,910 
72 



11,147 
5.856 



52 
90 

9.37 



77-795 



Cornwall and Devon [10] [n]. Although the lead mines of 
this area have shown no appreciable output for the last forty 
years, the production at one time was considerable. In 1856, 
for example, there were over fifty producing mines, with a 
total output of 13,112 tons of ore. In later years the output 
showed considerable fluctuation, with a general decline, and 
the industry is now practically extinct [io/p. 647]. 

The chief undertakings were situated in the neighbour- 
hoods of Ilfracombe (Combe Martin), Okehampton, Tavistock 
and Beer Alston, in Devon ; and near Callington, Menheniot 
(Herodsfoot, Wheal Mary Ann [12] etc.), Truro, Helston, 
Perranzabuloe, Chiverton and Newlyn Downs (East Wheal 



UNITED KINGDOM 45 

Rose, etc.), in Cornwall. In North Cornwall (Endellion, etc.) 
many of the lead veins yielded ores of antimony. 

The lead veins of the south-west of England are contained 
in Ordovician and Devonian slaty rocks (killas), and generally 
take a north and south direction, practically at right angles 
to that of the tin-gopper lodes, than which they are later in 
age. Moreover, the typical lead lodes are situated in the 
killas at some distance from the granite and well away from 
the tin-bearing localities. 

The ore is normally galena, almost always richly argen- 
tiferous, ores running from 30 up to 100 oz. of silver to 
the ton being common. At Beer Alston the proportion of 
silver, which was usually from 80 to 120 oz. to the ton, 
rose at one time to 140 oz. The average yield has been 
over 30 oz. to the ton. 

The galena is frequently accompanied by blende, and the 
veinstones carry quartz, calcite, fluorspar, carbonate and 
oxide of iron, and occasionally barytes. Not infrequently 
some copper ore is present. Rich silver ores and many beau- 
tiful carbonates, phosphates and arsenates were obtained from 
the upper parts of the veins. 

Although the lead-mining industry of this district is now 
practically extinct, Collins expresses the opinion [lo/p. 526] 
that there are large tracts of ground in East and North Corn- 
wall where traces of lead may be found in the cross- courses, 
which, if properly investigated, might prove as rich as any 
formerly worked. 

Mendip Hills [13]. Ores of lead and zinc are found here 
occupying fissures and cavities in the Carboniferous Limestone 
and overlying Triassic Dolomitic Conglomerate. The mining 
history of this area dates back to early times, and the activity 
of the Romans is evidenced by the pigs of lead, bearing Roman 
inscriptions, and other relics which have been found. No 
mining is carried on at the present time, though in recent 
years the old slag heaps, containing on an average 12 per 
cent, metallic lead, have been re-treated. 

In the neighbourhood of the surface the lead-bearing fissures 
are said to have carried oxides of iron and manganese, asso- 
ciated with clay, the galena being frequently altered to cerus- 



46 SOURCES OF SUPPLY OF LEAD ORES 

site. Very little blende was met with, though important 
deposits of calamine have been worked in the Dolomitic 
Conglomerate. It is most probable that deposits of blende 
await discovery at greater depth. 

This locality is notable for the occurrence of the rare oxy- 
chloride of lead, mendipite, and, as at Laurium in Greece, 
various secondary lead minerals occur in the old slag heaps, 
among which leadhillite, the sulpho- carbonate, deserves notice 



As operations in this area seem to have been of a shallow 
nature only, it would appear that the district deserves renewed 
attention in the light of modern methods. 

Derbyshire [15]. The lead deposits of this county occur 
in the Carboniferous Limestone as cavity fillings and meta- 
somatic replacements. The various forms assumed by the ore 
bodies are recognized by the miners under such terms as 
rakes, serins, flats and pipes, though the different types are 
not always distinctly separable, and they usually occur in 
association. Rakes, or rake- veins, are more or less vertical 
deposits in enlarged joints or faults, while similar occurrences 
in small cracks or fissures are recognized as serins. Flats are 
deposits in horizontal cavities formed along bedding planes ; 
one or more generally occur in association with a fissure 
filling, giving rise to a pipe. The term pocket is sometimes 
applied to deposits in chamber-like cavities on the side 
of a rake. 

The ores are confined almost entirely to the Carboniferous 
Limestone, very few veins extending into the overlying Yore- 
dale Shales. The deposits are said to be most productive in 
the upper part of the limestone, and it has long been an estab- 
lished fact that on passing downwards into the sheets of 
igneous rock (loadstones) which are intercalated with the 
limestone, they become impoverished or barren. 

The galena is accompanied by blende, and oxidized pro- 
ducts of both these ores occur. It is said that blende occurs 
more particularly in association with the harder beds of 
limestone, and that it increases with depth. Calcite, fluorspar 
and barytes are the gangue minerals, quartz being almost 
absent. Derbyshire is famed for the massive, fibrous and 



UNITED KINGDOM 47 

concentric variety of fluorspar known as Blue-John, which 
has been obtained exclusively from the Treak Cliff Mine, near 
Castleton. Much of the barytes is the earthy variety known 
as cawk. Many of the veins show a beautiful banding or 
crustification, the ores occurring in marginal or central layers, 
or alternating with, the other minerals. In the flats, especially, 
ribs of pure, massive galena are found. 

Although lead mining in Derbyshire was formerly an im- 
portant industry it has now declined considerably, and for 
several years past only one mine, Mill Close, in Darley Dale, 
has been in continuous operation for the production of lead 
ore [16]. This mine, which was reopened in 1859 after a 
period of idleness, was flooded from 1875 to 1877, but started 
operations again in 1883, when an entirely new dressing iplant 
was erected, and its output has been fairly regular since.* 
The lead concentrate produced carries about 80 per cent, of 
metal, and the mine yields also a small quantity of zinc ore 
annually [15]. The production in 1916 was 2,963 tons of 
lead concentrate, and 196 tons of zinc concentrate. 

Some of the Derbyshire mines are now worked for fluorspar 
and, to a less extent, for barytes. An account of the fluorspar 
occurrences is given by Wedd & Drabble [17], in whose paper 
will be found a useful map showing the distribution of the 
Derbyshire mineral veins. 

The Pennine Region [18]. This tract of country, compris- 
ing portions of the counties of Northumberland, Durham, 
Cumberland, Westmorland and Yorkshire, is characterized 
by an extensive outcrop of Carboniferous Limestone, in which 
a widespread deposition of lead ore has taken place. The 
Carboniferous Limestone Series consists of a group of strata 
composed chiefly of an alternation of limestones, cherts, sand- 
stones and shales, and the different members exert a very 
considerable influence upon the productivity of the veins. 
The ore occurs chiefly in the limestones and cherts, the sand- 
stones rarely affording any regular supply, while the shales 
are almost invariably poor or barren. In places the deposits 
extend into the overlying Millstone Grit, as at Grassington, 

* Quite recently the working of this mine has been interrupted by labour 
troubles. 



48 SOURCES OF SUPPLY OF LEAD ORES 

but the vertical extent of the productive ground is subject to 
great local variation. 

The ore bodies are chiefly infillings of fissures, very fre- 
quently faults, but there is also a good deal of metasomatic 
replacement of the limestones, particularly at the junction 
with some impervious bed. Deposits in which the ore occurs 
as irregular sheets, roughly parallel to the stratification of 
the enclosing strata, are known as flats, and have been an 
important source of ore supply. 

The galena, which on the whole is not notably argen- 
tiferous, though locally so, is commonly accompanied by 
blende, but the relative occurrence of the two ores is 
subject to considerable variation. The latter is met with 
more especially in depth, so that mines formerly worked 
exclusively for lead, such as those near Alston, are now pro- 
ducers of zinc. The gangue minerals, which comprise chiefly 
calcite, fluorspar and barytes, show a local distribution. 
Thus, while in Weardale the veins carry fluorspar, in Teesdale, 
immediately to the south, the corresponding material is barytes. 
These minerals are now frequent objects of exploration. 

The chief mining centres are situated in the neighbourhood 
of Hexham, Northumberland ; Upper Teesdale and Weardale, 
Durham [19] ; Alston Moor, Cumberland [20] [21] ; Brough 
and Dufton Fell, Westmorland ; and Upper Swaledale, 
Arkendale and Wensleydale, Yorkshire; but most of the 
mines are now derelict, though in past years they yielded a 
very large part of the British output of lead ore. Several of 
the workings have been re-opened from time to time and 
equipped with modern machinery, but often with little success, 
although one or two have become important zinc producers, 
notably the Nenthead Mine, near Alston, worked by the 
Vieille Montagne Company. Some of the mines are now worked 
for barytes, which is a common gangue mineral of the veins, 
but was formerly disregarded or thrown to waste, having at 
that time little value. In recent years most of the lead 
production has come from Weardale, where a group of 
mines are operated by the Weardale Lead Company. This 
company, which was formed in 1883, and reconstructed in 
1900, produced between 1884 and 1916, 117,222 tons of lead 



UNITED KINGDOM 49 

ore and, since 1898, 132,327 tons of fluorspar. Operations 
have been mainly conducted at the Boltsburn Mine fig]. 

Although it cannot be doubted that some of these mines 
still contain important reserves of lead ore, and more especially 
of zinc ore, the isolated situation of many of them, remote 
from railways, renders the question of transport a problem 
for serious consideration in connection with their working. 
In many cases the most satisfactory solution would appear to 
be the erection of aerial ropeways. 

The Lake District. The older Palaeozoic rocks of the Lake 
District, comprising portions of Cumberland and Westmor- 
land, contain many veins of lead ore, though at the present 
time less mining than formerly is carried on. The chief mines 
are located in the Caldbeck Fells (Roughtengill, etc.) and near 
Keswick (Threlkeld, Thornthwaite, Force Crag, etc.) in Cumber- 
land, and in the neighbourhood of Ullswater (Greenside, etc.) 
in Westmorland. Some of the properties are now worked for 
barytes. 

The galena, which contains appreciable quantities of silver, 
ores carrying from 25 to 35 oz. to the ton having been 
obtained, though the average is less, is commonly associated 
with blende and with more or less copper ore (chalcopyrite). 
Oxidized ores (carbonates, sulphates, phosphates and arse- 
nates) have been frequent, and the district is noted for several 
rare species, such as Una rite, leadhillite, caledonite, etc. 

One of the most productive mines in this district has been 
Roughtengill, extensively worked for lead, zinc and copper. 
Interesting and useful particulars of this and the other mines 
of the Lake District are given by Postlethwaite [22]. 

Shropshire, In the old lead-mining region of Shropshire 
and adjacent portions of Montgomeryshire, which has its 
centre in Shelve, lead-bearing veins are contained in Ordo- 
vician strata, and trend roughly east and west or north-west 
and south-east. The ore-bearing horizon is practically limited 
to the Mytton Grits, which immediately overlie the Stiper- 
stones Quartzite, at the base of the Ordovician sequence, and 
are bounded above by the Hope Shales. Blende accompanies 
the galena in many of the veins, and increases with depth. In 
those veins which have a north-westerly trend the gangue is 



50 SOURCES OF SUPPLY OF LEAD ORES 

calcite and galena occurs up to the surface, while the majority 
of the easterly and westerly veins have a barytes capping. 
Oxidized ores are rare, and the galena contains no appreciable 
amount of silver. 

There are numerous mines in the district, the majority of 
which are abandoned and flooded, but during the last few 
years a considerable portion of the area has been acquired 
by the Shropshire Mines, Limited, which has undertaken the 
construction of a deep drainage adit, the Leigh level, for 
the purpose of unwatering a large group of the mines. It 
is hoped that this, when completed, will enable the proper- 
ties to be worked to considerably greater advantage than 
formerly. 

The output of lead ore for this district reached a maximum 
in 1875, when 7,932 tons of concentrate were produced, 
chiefly from the Roman Gravels, Tankerville and Snailbeach 
Mines, since when the production has more or less steadily 
decreased, and at the present time there is only one mine 
(The Bog) from which any lead ore is obtained. By far the 
largest production has come from Snailbeach Mine, which, 
until recent years, maintained a continuous yearly output, 
but is now flooded. The mineral statistics of the district 
show that many of the properties have had a chequered 
history, and the productions of even the best mines rapidly 
declined before the cessation of operations. Subsequent re- 
opening of some of them does not appear to have met with 
any substantial success. It is said that a fall in the price of 
lead, combined with heavy pumping and transport costs, 
militated against successful operations, and as the latter items 
have now been seriously taken in hand by the present com- 
pany, the former by means of a deep adit and the latter by 
the erection of an aerial ropeway, it is hoped that the district 
may again become an important producer of ore. 

Although lead mining has so seriously declined, the produc- 
tion of barytes, on the other hand, has very considerably 
increased. This material is obtained largely from the old 
workings or adjacent veins, above water-level. It forms a 
gangue or capping to many of the veins, and was formerly 
largely disregarded, but now commands a ready sale. 



UNITED KINGDOM 51 

Lead mining in this district dates back to Roman times, as 
evidenced by the pigs of lead and other remains which have 
been found. An account of the geological and mining fea- 
tures of the area was given by Morton in 1869 [23]. 

Alderley Edge. Some of the Triassic sandstones in the 
neighbourhood of Macclesfield, Cheshire, noted more especially 
for their ores of copper, have likewise yielded lead ore in the 
form of cerussite, galena, pyromorphite and vanadinite. 
Although attempts to work these rocks for their lead content 
have met with no substantial success, the deposits bear a 
close similarity to those which have been extensively exploited 
near Mechernich and Commern, in Germany, described here- 
after (p. 88). 

A rare vanadate of lead and copper from this locality has 
been described under the name of mottramite [24]. 

Flintshire and Denbighshire. The Carboniferous rocks found 
in these counties contain a number of veins carrying ores of 
lead and zinc which have been of considerable commercial 
importance, the most productive undertakings being the 
Halkyn Mines near Holywell, in Flintshire, and the Minera 
Mine near Wrexham, in Denbighshire. The latter, now shut 
down, at one time the most productive lead mine in Britain, 
became in its later years chiefly a producer of zinc ore. 

The Halkyn deposits occur for the most part in faults travers- 
ing the Carboniferous Limestone and overlying chert beds of 
the Millstone Grit. There are two well-marked sets of veins, 
and it is interesting to note that those which have an east and 
west trend, and appear to be older, carry both argentiferous 
galena and blende, while the later, north and south veins, or 
cross courses, contain practically no blende, and the galena is 
much poorer in silver. The veins are said to have been most 
productive below the pyritiferous Holywell shales, which evi- 
dently exerted a control upon the deposition of the ore. Their 
characters and mode of occurrence are fully described by 
Aubrey Strahan in the Geological Survey Memoirs of the 
district [25] [26]. In the upper workings carbonate ores 
(cerussite and calamine) were abundant. 

The mines of the Halkyn district are drained by a deep 
adit, about four miles long, which, at the time it was con- 






52 SOURCES OF SUPPLY OF LEAD ORES 

structed, gave a new lease of life to the district, and enabled 
the mines, which one after another had been compelled to close 
down owing to excessive pumping charges, to recommence 
operations. Subsequently, however, the workings extended 
below the adit level, and the same difficulty again caused aban- 
donment of the properties. A new adit, about six miles 
long, to drain the district to a depth of 200 ft. above sea- 
level, was being driven by the Halkyn District Mines Drainage 
Co., but the work is now stopped for financial reasons [82/pp. 

15-17]. 

Carnarvonshire, etc. -Veins carrying ores of lead and zinc 
occur in the older Palaeozoic rocks of Carnarvonshire, as 
at Bettws-y-coed, Llanrwst, Trefriw and Trecastell, in the 
Conway Valley. Only a few mines on these deposits are in 
operation, however, and with little success, the total yearly 
output of lead ore for the last few years averaging only a 
few hundred tons. The principal property, Trecastell Mine, 
produced in 1916, 132 tons of dressed lead ore and 105 tons 
of zinc ore. 

Lead ore is found in the well-known copper deposit of Parys 
Mountain in Anglesey, though the occurrence is not of much 
commercial interest. Occasionally small quantities of lead ore 
were produced, and also zinc ore, from this source. This is 
the original locality for anglesite, which is said to have occurred 
here at one time in some abundance. 

Central Wales. Lead veins, traversing slaty Palaeozoic 
rocks, occur over a large part of Central Wales, principally 
in the county of Cardiganshire, and were at one time the 
scene of great mining activity. The deposits have been 
fully described by Warrington Smyth [27]. The veins trend 
roughly north of east and south of west, but their directions 
are subject to much local variation. They carry both galena 
and blende, the latter, which increases with depth, being at 
the present time the chief ore worked. The fissure fillings 
are largely composed of brecciated country rock cemented by 
quartz and calcite, in which the ore occurs irregularly dis- 
tributed. Calcite is less abundant than quartz, but its presence 
is said to favour the occurrence of ore. Barytes is uncommon, 
while fluorspar is said to be absent. In some places pyrite 



UNITED KINGDOM 53 

is very abundant. The silver content of the galena is, on the 
average, not high, though in some cases it reached as much as 
30 oz. to the ton. 

Only a few mines are now being worked in this area, and 
many of the largest and most important properties are dere- 
lict. The majority of them are remotely situated and difficult 
of access. The well-known Van Mine, near Llanidloes in 
Montgomeryshire [28], on the eastern edge of the district, has 
continued operations up to the present time, and produced in 
1916, 326 tons of dressed lead ore and 18 tons of zinc ore. 

South Wales. Occurrences of galena in the Carboniferous 
and overlying Triassic rocks of the South Wales coalfield have 
been frequently noted, though so far they have proved of no 
commercial importance, attempts to mine them having been 
unsuccessful. 

Isle of Man. The lead ores of this region occur in veins 
traversing Cambrian slates and associated granite. The 
galena, which is richly argentiferous, is accompanied by a 
considerable amount of blende, and the chief veinstones are 
quartz and calcite. The occurrence of plumosite, an antimonial 
lead sulphide, is noteworthy. 

The lead production of the Isle of Man has been very con- 
siderable, the main output coming from the famous Foxdale 
and Great Laxey Mines. At the present time the former 
property is abandoned, while the latter has become chiefly a 
zinc producer. In 1916 this mine produced 208 tons of lead 
ore and 865 tons of zinc ore. 

At Foxdale the main lode was traced for a distance of be- 
tween two and three miles, and in places was as much as 40 
feet in width. Mining operations extended to a depth of 
about 2,000 ft. At Laxey the deposit carried a fair quantity 
of copper sulphides, and at one time copper ore was produced. 

The ore deposits of this region have been fully described 
by G. W. Lamplugh [29]. 

Leadhills and Wanlockhead. These two groups of mines, 
which adjoin one another, the former being in Lanarkshire 
and the latter in Dumfriesshire, operate upon a system of 
veins which extend over a tract of country measuring roughly 
two miles north and south and three miles east and west. 



54 SOURCES OF SUPPLY OF LEAD ORES 

Mining operations have been continuous for over 200 years, 
and the district has yielded about 95 per cent, of the entire 
lead output of Scotland. 

The veins occur in slaty rocks of Ordovician age, and carry 
both galena and blende, the latter having been found so far 
only in subordinate quantity. The chief gangue mineral is 
calcite, though barytes occurs also. The upper portions of 
the veins formerly yielded a great variety of oxidized products, 
for which this district is famous, including several rare basic 
sulphates and sulpho- carbonates, only occasionally found in 
Britain. 

Cerussite, anglesite and pyromorphite have all been raised 
as ores at one time or another. 

An interesting account of the mining and history of the 
district, with a map of the veins, has been given by John 
Mitchell [30], from whose description the following particulars 
are taken. For the last fifty-two years, up to the end of 1917, 
Leadhills produced 88,796 tons of dressed lead ore, the output 
for the last ten years of that period being 18,162 tons, while 
during the same time Wanlockhead produced 91,509 tons of 
lead ore and 8,654 tons of blende, the corresponding figures 
for the last ten years being 25,324 and 6,513 respectively. 
The returns before the period given are difficult to obtain. 
In 1914 the crude ore of Leadhills yielded 10 per cent, of lead 
concentrate, while that of Wanlockhead gave 4-95 per cent, 
of lead concentrate and 1-62 per cent, of zinc concentrate. 

Owing to difficulties experienced with the water, and the 
heavy pumping expenses necessary, a scheme for unwatering 
the mines by means of a deep adit has been under considera- 
tion. This adit, starting from Enterkinfoot, and having a 
total distance of about 7 miles, would intersect the veins 
at a depth of nearly 1,000 ft., and would take from five to 
six years to complete. It is anticipated that such an under- 
taking will not only render possible the re-opening of some of 
the mines, but will at the same time prove a large extent of 
unexplored ground [8/p. 34]. 

Strontian (Argyllshire). The lead ores of this neighbour- 
hood, which occur in veins traversing gneissic rocks near a 
granite outcrop, were first mined at the beginning of the 






UNITED KINGDOM 55 

eighteenth century, and operations were continued for about 
150 years. The locality is notable for having yielded the 
mineral strontianite, in which strontium was first discovered. 

The galena is associated with calcite and barytes, and 
interesting occurrences are strontianite and celestine, and the 
secondary barium- and strontium-bearing zeolites, harmotome 
and brewsterite. 

Although no lead is now raised at Strontian attention has 
recently been directed to the locality as a possible source of 
barytes. According to the Geological Survey there is a con- 
siderable quantity of galena lying in some of the spoil heaps 

[3I/P- 88]. 

Ireland. About 80 per cent, of the lead ore production of 
Ireland has come from the Luganure Mines in County Wicklow, 
which were operating up to about the year 1892. Since then 
the output of lead ore from Ireland has practically ceased 
[8/p. 15]. The veins from which this ore was derived occur 
in a belt of mineralized granite and slate which stretches 
southward into Wexford. Lead ores occur principally in the 
northern portion of this tract, in Glendasane, Glenmalure, 
and Glendalough, while to the south copper ore is abun- 
dant and was long worked at the well-known mines of the 
Vale of Avoca. The mines of this region were described by 
Warrington Smyth in 1853 [32]. 

Ores of lead have occasionally been mined in the Car- 
boniferous Limestone and older rocks of other parts of Ireland, 
as in Galway, Sligo, Clare, etc., but the output has never been 
large. 

Consumption of Lead in the United Kingdom 

The amount of lead consumed by any particular country 
in a given period may be roughly gauged by subtracting the 
amount of exports from the sum of the domestic production 
and imports, thus : 

Consumption = (Domestic Production + Imports) - Ex- 
ports. 

Such a computation, however, takes no account of any 
unused stocks remaining in the country, and in any case is 
only approximate. A reliable estimation of the amount of 
5 



56 SOURCES OF SUPPLY OF LEAD ORES 

lead consumed by a country such as, for example, the United 
Kingdom, in which imports and exports show considerable 
overlapping, is a by no means simple matter, on account of 
the many factors which have to be taken into consideration. 
Thus, the lead stocks of the country may be derived partly 
from domestic ores, partly from imported ores and partly from 
metal imported as such ; and in the case of the former two it 
is necessary to know the grade of concentrate a very variable 
factor before making any reliable estimation of the metallic 
yield. Against these items one has to consider, in the matter 
of exports, the lead contained in domestic ores exported as 
such, and lead derived both from domestic and imported ores 
and exported as metal. The question may be further compli- 
cated by re-export of material. 

In the case of the United Kingdom the computation for 
1914, the last year for which normal statistics are available, 
may be approximately made as follows, all quantities being 
given in long tons : 

Tons. Tons metal. 
Domestic production of ore (say 75% metal) = 26,013 = 19,510 

Imports of lead ore (say 60% metal) . = 28,436 = 17,062 
Imports of metallic lead ... = 224,916 

Total imports of metal . . = 241,978 

Exports of lead ore (say 75% metal) . = 3,715= 2,786 
Exports of pig lead ... = 21,655 

Total exports of metal . . = 24,441 

The consumption was therefore : 

(19,510 + 241,978) 24,441 = 237,047 long tons. 

In this computation the metallic content of the domestic 
ores is taken at 75 per cent., since this has been the average 
grade of the concentrates produced for many years past. On 
the other hand, the grade of imported concentrates has been 
put at only 60 per cent., as these are likely to vary within 
fairly wide limits, and some may be as low as 50 per cent. It 
is further assumed that all exported ore is of domestic origin, 
as seems most likely. 

It will be noticed to what a large extent the United Kingdom 
is dependent upon imported material, its own deposits, now 



UNITED KINGDOM 57 

largely abandoned or impoverished, being quite inadequate 
to supply the demand, even were all the ore produced retained 
in the country. In fact, the amount of metal obtainable from 
domestic ores is somewhat less than that exported, so that it 
may be said that under existing conditions we are entirely 
dependent upon imported material for domestic consumption. 

The production of dressed lead ore in the United Kingdom 
for the years 1915 to 1919 inclusive is given in the table on 
p. 43. Tables Nos. VI, VII, VIII, IX, on pages 58-60, show 
the quantities and values of recent exports and imports of 
dressed lead ore and of lead, respectively, and the various 
countries of reception and origin. 

A perusal of these tables brings out the serious effect of 
the war both on exports and imports, the figures for that 
period showing very considerable decreases. The exports, 
especially, reflect the condition of affairs. Thus, the closing 
of the Belgian and German markets, to which previously the 
bulk of the exported ore was consigned, reduced the exports 
of lead ore to insignificance. Similarly a marked decline is 
observable in the quantities of pig lead exported, though in 
this case the situation seems to have arisen from the lack of 
shipping rather than from the closing of the markets. To 
the producer, however, the position was more than compen- 
sated for by the increased home demand, which, in point of 
fact, exceeded the supply, and resulted in a rapid advance of 
price, as will be seen from the table on p. 12. 

Previous to the war the bulk of the pig lead manufactured 
in the United Kingdom found its way to Canada, France and 
Russia, but during hostilities these markets fell away. Dur- 
ing that period Canada imported large quantities from the 
United States (see Table XI). The exports to France prac- 
tically ceased during 1916-17, and the present position as 
regards Russia is naturally very uncertain. 

The imports of dressed lead ore into the United Kingdom 
have been derived, on an average, in about equal proportions 
from the British Empire and from foreign countries, the main 
contributing country in the former case being Australia, while 
in the latter instance the largest supply has come from South 
America, During the war these sources of supply were, on 



SOURCES OF SUPPLY OF LEAD ORES 



Table VI 

Exports of Dressed Lead Ore from United Kingdom * 
In long tons (2,240 Ib.) 



To 


1911. 


1912. 


1913. 


1914. 


I9I5- 


1916. 


1917. 


1918. 


1919. 


Belgium 
Germany 
Other countries . 


1,309 
1,248 
283 


1,604 
492 
316 


2,649 
532 
377 


2,549 
945 

221 


86 


152 


210 


18 


478 


Totals . 


2,840 


2,412 


3,558 


3.715 


86 


152 


2IO 


18 


478 



* Annual Statement of Trade of United Kingdom. 

Table VII 
Exports of Pig Lead and Manufactures from United Kingdom * 

In long tons (2,240 Ib.) 





1915. 


1916. 


1917. 


1918. 


1919. 


1920.1 


To British countries : 














India 


4,723 


4,36o 


2,641 


1,866 


2,947 


\ 


Ceylon 


1,265 


836 


338 


217 


36i 


j4> 2 5 


British East Indies 


2,162 


709 


39 


2 


751 





Canada 


1,019 


927 


155 


I 


382 


5,207 


South Africa 


1,447 


1,010 


372 


IOI 


M5 


181 


Other British countries 


i,337 


2, 1 60 


352 


I 7 8 


I, in 





Totals . 


",953 


IO,OO2 


3,897 


2,365 


5.697 


9,653 


To foreign countries : 














France 


4,243 


972 


5 


29 


1,810 


i,37 


Russia 


12,024 


10,675 


2,398 




382 


563 


Sweden 


1,618 


688 


149 


2 


1.536 


1,960 


Denmark . 


2,098 


562 


26 


2O 


504 





China 


227 


256 


189 


II 


2,2IOf 


737t 


Japan 


762 


893 


741 


727 


5,647 


1,381 


ava .... 


1,969 


2,493 


1,592 


1,676 


1,609 





South America . 


1,592 


831 


57 


5 


678 





Other foreign countries 


3,907 


1,038 




83 


4.279 


12,310 


Totals . 


28,440 


18,408 


5,467 


2,553 


18,655 


18,321 


Grand totals . 


40,393 


28,410 


9,364 


4,918 


24,352 


27.974 



* From Annual Statements of Trade of United Kingdom, and monthly 
trade and navigation of U.K. 

t Including Hong Kong. J Nine months only. 



UNITED KINGDOM 



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SOURCES OF SUPPLY OF LEAD ORES 



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UNITED KINGDOM 61 

the whole, maintained, the drop in the total amount of im- 
ports being due chiefly to the failure of the European supplies, 
notably those of Germany, France, Belgium and the Nether- 
lands. The large increase during 1917 of the quantity of ore 
imported from India is an important feature. 

As regards imports of metallic lead, by far the largest 
amount obtained within the Empire has come from Australia, 
the tonnages during latter years having exceeded those from 
any other country. In fact, during 1917, the quantity was 
greater than that from all other countries combined. Previ- 
ously our largest imports came from Spain, but the tonnages 
from this source declined considerably during 1916-17. The 
failure of supplies from Belgium, Germany and France during 
the war was partially balanced by the increased amounts re- 
ceived from Greece and Italy. 

ASIA 
INDIA 

Galena occurs in many parts of India ; but the only deposits 
being worked on a large scale at present are those of Bawd- 
win, Upper Burma. A description of the region, together 
with its history, appears in the Imperial Institute monograph 
on Zinc Ores (p. 33-34), but the following notes, by J. Coggin 
Brown [33], refer more particularly to the nature and struc- 
ture of the principal ore- body (The Chinaman) : The main 
ore-channel at Bawdwin is 8,000 ft. long, and probably 
from 400 to 500 ft. wide, and is in a nearly vertical zone of 
combined faulting and shearing in rhyolite tuffs. The China- 
man ore-body is an enormous replacement deposit of argen- 
tiferous lead-zinc ore occurring on the hanging-wall side of 
the ore-channel. The axis of the thickest part of the sulphide 
ore strikes approximately 25 W. of N., and dips 70-8o W. 
The hanging-wall is more or less regular, but the foot-wall is 
ill- denned, and there is a gradual passage from the solid 
mixed-sulphides of lead and zinc through a second-grade ore 
composed of dark grey tuffs infiltrated with silica, and con- 
taining nests and strings of sulphides, in which the metallic 
sulphides gradually become poorer, until unaltered rhyolite 



62 



SOURCES OF SUPPLY OF LEAD ORES 



tuff and, in some cases, true rhyolite are found. An ore carry- 
ing 24 per cent, of lead and 14 per cent, of zinc assayed 17 oz. 
of silver to the ton, and ore carrying 30 per cent, of lead and 
26 per cent, of zinc assayed 40 oz. of silver per ton. 

Almost the entire output of lead ore from India comes 
from the Bawdwin mines. From 1910 to 1916 inclusive the 
company (now the Burma Corporation, Ltd.) working the 
mines smelted a large quantity of slag left by the old Chinese 
workers, and during those years comparatively little ore was 
raised, but by 1915 the greater part of the slag had been 
worked off. In 1916 the output of lead ore from Bawdwin 
amounted to nearly 9,000 tons, and in the two following years 
to upwards of 50,000 tons per annum (see Table I, p. 35). 
The exports from India of lead for recent years is given in 
Table X. 

Table X 

Exports of Lead from India * 
In long tons (2,240 Ib.) 





1911-12. 


1912-13. 


1913-14' 


1914-15. 


1913-16. 


1916-17. 


1917-18. 


1918-19. 


To British countries : 
United Kingdom 
Ceylon 
Other British countries 

Totals : 
British countries . 

To foreign countries 
Grand totals 


9,870 

id 


5,785 
1.307 
30 


2,268 
1,110 

43 


4.372 

2,036 


5,096 
4.031 

554 


1,915 
4.536 
1,109 


4,121 

6,093 
133 


349 

5,897 
850 


10,031 


7,122 


3,421 


6,408 


9,681 


7,56o 


10,347 


7,096 


146 


190 


IO 


101 


1,165 


2,792 


222 


2,202 


10,177 


7.3" 


3.431 


6,509 


10,846 


10,352 


10,569 


9,298 



* Annual Statement of Sea-borne Trade of India. 
(Fiscal year ends on the 3ist March in each year.) 



AFRICA 
EGYPT 

Important quantities of lead and zinc ores have recently 
been produced from the ancient mines at Gebel Rosas, near 
the Red Sea, which were reopened in 1913 by the Compagnie 
Francaise des Mines de Laurium. The ores occur as replace- 



EGYPT 63 

ments in limestone, and consist of sulphides and carbonates. 
Analyses show up to 58 per cent, lead and 37 per cent. zinc. 

NIGERIA 

Lead and zinc ores occur in the Abakaliki district [34] [35]. 
A lode occurring at Alusi Hill, Ifotta, near Enyiba, which has 
been worked by the natives, carries galena, blende and 
siderite, and other deposits have been recognized in the 
vicinity. The following table, which is taken from the mono- 
graph on Zinc Ores, p. 35, gives the results of an examination 
undertaken at the Imperial Institute of six bulk samples from 
the Ifotta lode : 





Lead. 


Zinc. 


Copper. 




SilTer. 






Percent. 


Percent. 


Percent. 




Per toa. 




I. 


65-49 


0-73 


trace 


2 


OZ 10 dwt. 


15 gr- 


2. 


55-21 


6-99 


0-56 


2 


6 


9 , 


3- 


38-87 


3-49 


trace 


I 


8 


2 , 


4- 


33-31 


I'll 


0-088 


I 


.. 19 


20 , 


5- 


24-65 


1-33 


0-04 


I 


18 


'3 , 


6. 


0-82 


30-40 


O-I2 




7 


12 , 



RHODESIA 

The deposit of Broken Hill, in North- Western Rhodesia, 
consists of irregular masses and impregnations in crystalline 
limestone. Galena and blende occur in intimate association, 
and there is an extensive development of oxidized ore. Owing 
to difficulties of treatment of the ore these deposits were 
for many years of little commerical value, but recently have 
received renewed attention with successful results. 

SOUTH-WEST PROTECTORATE 

Deposits in limestone carrying ores of lead, in association 
with those of copper and zinc, have been mined in the Otavi 
Mountains, and small quantities of ore exported to Germany. 
This colony has also sent considerable amounts of ore to the 
United States. During 1918 the Otavi Co. exported 7,358 
long tons of ore containing 12 to 22 per cent, of lead. 



64 SOURCES OF SUPPLY OF LEAD ORES 

SUDAN 

Lead ores are said to occur in Jebel Kutum, north of Kobe, 
in Darfur [36], but no commercial production has yet been 
recorded, although the deposit is stated to have been worked. 

UNION OF SOUTH AFRICA 

Deposits of lead ore are known in many places in the South 
African Union, but, on the whole, they have received but 
little attention, and their possibilities have not yet been fully 
proved. Throughout the dolomitic rocks of the Transvaal 
irregular deposits, pockets and impregnations of galena are 
found, but many of these are small and hardly of commercial 
importance, and in almost all cases decrease in value with 
depth. The most important occurrences hitherto mined are 
those of the Malmani district, where the ore is found in pipe- 
like deposits and impregnations in the Malmani Dolomites of 
the Transvaal System. The primary ores consist of galena 
and blende, while hemimorphite, calamine and copper carbon- 
ates are found in the oxidized zone. Small quantities of 
cinnabar are found. At Leeuwkloof, in the Pretoria district, 
the deposit consists of a large replacement of dolomite at its 
contact with the overlying shales of the Pretoria Series. 
About 700 tons of ore, averaging 73 to 75 per cent, of lead, 
and 2 to 4 oz. of silver to the ton, have been extracted from 
this deposit. A similar, but smaller, ore-body is mined at 
Rhenosterhoek, in the Marico district, where the ore carries 
9 to 15 oz. of silver to the ton. 

Veins carrying galena, sometimes associated with ores of 
gold, silver, copper and cobalt, are found in the Pretoria 
Series, and have been mined in the Pretoria, Marico and 
Rustenburg districts. In the Pretoria district the chief 
operating property is the Transvaal Silver Mine, where argen- 
tiferous galena, associated with iron and copper pyrites, copper 
carbonates and tetrahedrite, in a gangue of siderite, is found 
in a vein connected with a diabase dyke. At Edendale, a 
vein in the Pretoria Series, carrying galena and blende in a 
gangue of quartz and calcite, has been worked. 



UNION OF SOUTH AFRICA 65 

A vein of lead ore was formerly worked at Argent, fifty miles 
east of Johannesburg, and similar deposits are known in 
Northern Transvaal, Waterval Onder, Natal and Gordonia. 
At Potgietersrust the deposit occurs in altered (Pre- Cambrian) 
granite. 

Other localities in the Transvaal where lead is or has been 
mined are Broederstroom, Dwarsfontein and Roodekrans, in 
the Pretoria district ; Witkop, Bokkraal, Buffelshoek, Riet- 
spruit, and Doornhoek, in the Marico district ; and Windhuk, 
hi the Pietersburg district. Many of the mines were closed 
down on account of the war. 

In the Cape Province lead ores occur in several places, both 
as dolomitic replacements and as vein deposits. The best- 
known occurrence is that of the Maitland Mine, near Port 
Elizabeth, where galena occurs in a vein, in association with 
ores of copper, silver and antimony. Other occurrences are 
at Banghoek, forty miles west of Hopetown ; in quartz veins 
at Knysna ; at Richmond ; and in the Beaufort West and 
Victoria West districts. In the Van Rhynsdorp district a 
large vein, carrying pyromorphite at the surface, has been 
located. Deposits are known to occur also in Bechuanaland 
and in Damaraland, and in the Bokkeveld Series of the Cale- 
don and Swellendam districts, but many of these appear to be 
of little commercial importance. 

In Natal galena has been found at Umsingi and in Umvoti 
County, but no extensive deposits are known. In the schists 
of the Mfongosi and Ngobevu Valleys, near the Tugela River 
in Zululand, a quartz vein carrying small quantities of galena 
has been prospected, but so far the results are not encourag- 
ing [37]- 

NORTH AMERICA 

BRITISH WEST INDIES 

Lead ore is worked on a small scale in this region, as also 
in British Guiana, and insignificant quantities of lead are 
exported at irregular intervals, chiefly to Canada. At the 
present time these sources are quite unimportant. 



66 



SOURCES OF SUPPLY OF LEAD ORES 



CANADA 

Several important deposits of lead ore are worked in this 
country, and the annual production of lead is now about 
20,000 tons, as will be seen from the annexed table, which has 
been compiled from the Annual Reports of the Department 
of Mines : 

Production of Lead in Canada 

In metric tons (2,204 tt>.) 





1911. 


1912. 


1913. 


1914. 


1915. 


1916. 


1917. 


1918. 


1919. 


British Columbia . 


10,791 


16,226 


17,072 


16,465 


20,552 


17,766 


13,377 


21,594 


19,915 


Yukon, etc. . 







17 


22 


457 


1,062 


1,403 


1,726 




Totals . 


10,791 


16,226 


17,089 


16,487 


21,009 


18,828 


I4,78o 


23,320 






In 1917 the total production of lead concentrate was 
58,801 tons. The chief deposits are situated in British 
Columbia, while less important ones occur in Quebec and 
Ontario. For full particulars regarding the Canadian lead 
ore occurrences reference may be made to the Annual Reports 
and other publications of the Department of Mines. 

British Columbia. By far the greatest production of lead 
ore in Canada comes from this province, chiefly from the 
Slocan district. 

The veins of the Slocan district [38] occur in the clay slates 
and associated limestones and quartzites of the Slocan Series, 
believed to be of Pre- Cambrian age, and are connected with 
intrusions of granite. The ores comprise argentiferous galena, 
blende, and argentiferous tetrahedrite, with pyrite and chal- 
copyrite. Native silver occurs in the secondary zone. The 
common gangue is siderite or an allied carbonate, but quartz 
predominates where the veins intersect the igneous rocks. 
Blende and pyrite increase with depth, but many of the veins 
show a general impoverishment. Where the fissures intersect 
the bands of limestone there is frequently a good deal of meta- 
somatic replacement and large shoots of ore occur. In these 
places the proportion of silver in the galena is much increased. 



CANADA 67 

The chief producing property in 1917 was the Surprise 
Mine ; others are the Standard, Lucky Jim, Galena M. & M. 
Co., and the Slocan Star. Much of the ore is smelted at Trail. 

In the East Kootenay district there are important lead and 
zinc deposits from which a considerable production has re- 
cently taken place, notably from the Sullivan Mine. At the 
Monarch Mine a mill having a capacity of 80 tons a day is in 
operation, and the ore obtained is dressed to yield both lead 
and zinc concentrates. The former, which carries 67 per cent, 
lead, with under 9 per cent, zinc, and about 5 oz. of silver 
per ton, has been sent to Trail for smelting. 

The Ainsworth district contains veins traversing schists, 
quartzites, and crystalline limestones of Pre-Cambrian age. 
In the latter rocks the deposits are irregular metasomatic 
replacements. The ores consist of galena, containing only a 
small quantity of silver, and blende, associated with pyrite, 
pyrrhotine and chalcopyrite. A typical sample of the ore 
is said to have yielded 20-8 per cent, zinc, 11-7 per cent lead, 
and 2-5 oz. of silver per ton. Recently producing mines are 
the Whitewater of West Kootenay, and the Utica of Paddy 
Mountain. 

Lead and zinc deposits occur also in the Nelson district, 
near Salmo, from which some production has taken place in 
recent years. 

In the Yukon territory, near the borders of Alaska, deposits 
of galena, very rich in silver, have been opened up, and the 
production from this source has been rapidly increased within 
the last few years. The most productive undertaking has 
been the Silver King Mine, near Mayo. There is little doubt 
that many important deposits exist in this region, but the 
difficulties of transport at the present time militate against 
successful operations. 

Ontario. Although there are several occurrences of lead 
ore known in this province, but little work has been done 
upon them, and the output of ore has been irregular and 
intermittent. Many of the mines from which lead has been 
produced in the past are now abandoned. Accounts of the 
occurrences may be found in the Reports of the Ontario 
Bureau of Mines. 



68 SOURCES OF SUPPLY OF LEAD ORES 

Some of the best known deposits are those of the Long Lake 
Mine, in Frontenac County ; the Katharine Mine, in Hastings 
County ; and the Victoria and Cascade Mines of Garden 
River, near Sault Ste. Marie. 

In the Long Lake Mine, galena, intimately associated with 
blende, occurs as irregular replacements in crystalline lime- 
stone. Some of the ore-bodies are of large dimensions. 
The galena is argentiferous and the ore may contain up to 
20 oz. of silver to the ton. 

In the Katharine Mine, in Lake Township, Hastings County, 
operations have been conducted upon a vein carrying argen- 
tiferous galena and blende, associated with pyrite and pyrrho- 
tine, in a gangue of calcite and siderite. The occurrence of 
ozokerite is noteworthy. The country rocks consist of schists 
and diorite. 

Quebec. The only productive lead mine at present in this 
province is the Notre-Dame-des-Anges, in Portneuf County. 
The deposit consists of small veins and impregnations in a 
micaceous quartzite, and there are two well-defined zones of 
ore. The ore consists of a more or less intimate mixture of 
galena and blende, associated with sulphides of iron and 
copper. Small quantities of gold and silver are present also. 
Some output was recorded from this mine during 1917. 

Deposits containing galena and blende, intimately asso- 
ciated, have been mined on Calumet Island, Pontiac County, 
but difficulties connected with the treatment of the ore caused 
abandonment of the property, although a modern concen- 
trating plant was installed. The ore occurs in irregular, 
pockety deposits in diorite associated with limestone and 
gneiss. 

Nova Scotia. No commercial production of lead ore is 
recorded from this province, although one or two deposits 
have been located. In Inverness County veins carrying galena, 
blende, pyrrhotine and mispickel occur in schists at Faribault 
Brook. 

Recent Canadian exports and imports of lead are shown in 
Tables XI and XII. 



CANADA 



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70 SOURCES OF SUPPLY OF LEAD ORES 

NEWFOUNDLAND 

At many places in this island lead ore has been found 
and, in some cases, worked, though, on the whole, with but 
poor success. The deposit at Buchan's River, Red Indian 
Lake, contains lead, zinc, silver and copper, with some gold, 
and has been exploited to a depth of several hundred feet. 

AUSTRALASIA 
AUSTRALIA 

Australia is by far the largest producer of lead ore in the 
British Empire, the output being derived almost entirely from 
the mines of Broken Hill. 

New South Wales. The famous deposit of Broken Hill [39] 
[80], discovered in 1883, was first worked for silver, then for 
silver and lead, and in recent years largely for zinc. At the 
present time it is one of the largest lead-zinc deposits in the 
world. The main ore-body, the outcrop of which formed the 
crest of the hill but has now been practically all removed, 
stretches for a distance of about one and a half miles in a north- 
east and south-west direction, with a maximum width of 100 ft. 
It was formerly classed as a large saddle reef, with downwardly 
tapering limbs, but the north-west portion is now regarded 
as the main ore-body, the south-east limb being a lobe or off- 
shoot from this. This portion of the deposit is impersistent 
and often thins out. There are other and smaller lodes in the 
vicinity. The country rock consists of highly metamorphosed 
sediments, folded into an anticline and penetrated by masses 
of granite and basic dykes. 

The deposit has been followed to a depth of 3,000 ft., and 
still contains large bodies of ore. The gozzan, which ex- 
tended downwards for about 300 ft., and varied in width 
from 20 to 100 ft., carried siliceous and manganiferous 
limonite, haematite and kaolin. Below this occurred large 
masses of cerussite and anglesite, with oxides and carbonates 
of copper, and abundant haloids of silver (cerargyrite, embolite 
and iodyrite). The proportion of silver in the ore was in 
places as much as 300 oz. to the ton. The ore of the primary 
sulphide zone, which was reached about 1893, consists of a 



AUSTRALIA 71 

fine-grained mixture of galena and blende, associated with 
sulphides of iron, copper and arsenic, in a gangue of rhodonite, 
calcite, quartz and garnet. Wulfenite and fluorspar are rare 
occurrences. 

Owing to the intimate association of the galena and blende 
their separation cannot be carried out by ordinary methods, 
and flotation is resorted to with highly successful results. 
The large quantities of tailing and residue, amounting to 
between five and six million tons, which accumulated in the 
earlier days when the zinc could not be successfully ex- 
tracted, are now being similarly treated. They contain about 
18 per cent, of zinc, with some lead and silver, and yield im- 
portant productions. 

Formerly the crude sulphide ore averaged about 25 per 
cent, each of lead and zinc, with 25 oz. of silver to the ton, 
but the grade is now lower and does not exceed 15 per cent. 
The dressed products consist of (i) lead concentrate, carrying 
about 65 per cent, lead, with 6 per cent, zinc, and (2) zinc 
concentrate, containing about 45 per cent, zinc, and 5 to 8 
per cent. lead. 

There are several companies mining the deposit, and the 
annual output of crude ore has been about 1,500,000 tons. 
Since 1917, however, production has been much retarded on 
account of local industrial troubles and general strikes. 

Previous to the war about half the lead concentrate was 
smelted at Port Pirie, the remainder being sold chiefly to 
German firms and smelted in Belgium and Germany. At the 
present day the whole of the smelting is done in Australia, 
principally at Port Pirie. 

Queensland. The Burketown district, in the north-western 
corner of the State, contains several deposits of galena asso- 
ciated with blende, typical samples of the ores yielding on 
the average 13 per cent, galena and 10 per cent, blende. 
There are several groups of claims, such as the Silver King, 
Banner, Watson's, Tunnel Hill, Anglo- American, Britannia 
and Greater Britain. Many of the deposits are low-grade and 
of more importance as sourqes of zinc than of lead. The 
galena is commonly argentiferous. 

The Mount Barker Mine, in the Eungella Goldfield, has 
6 



72 SOURCES OF SUPPLY OF LEAD ORES 

been worked for argentiferous galena, but the presence of a 
considerable amount of intimately associated blende has 
rendered the ore difficult of treatment. 

South Australia. The output of metallic lead from this 
State is due to the smelting of Broken Hill ore at Port Pirie. 
No important deposits of lead ore have as yet been located. 
Victoria. Although several occurrences of lead ore, asso- 
ciated with zinc, have been located in this State, so far no 
mining undertakings of any importance have been carried out 
upon them. 

West Australia. The chief lead occurrences in this State 
are situated in the Northampton district, extending over an 
area of about fifty miles in length. The veins, which are 
usually small but of considerable length, occur in garnetiferous 
granite in association with parallel basic dykes, and are often 
found along the junctions of the latter with the granite. The 
ore is mainly a high-grade galena and frequently occurs in 
shoots of from 500 to 1,000 ft. in length. Several of the 
veins yielded copper ore at the surface, but this gave place in 
depth to a mixture of copper and lead, and, finally, to lead 
ore only. In the Surprise Mine, at Geraldine, the ore assays 
50 per cent, lead over a width of 10 ft. ; the quantity of silver 
present is small, averaging only about half an ounce to the 
ton. The concentrates produced in this district average about 
70 per cent, metal. 

According to a recent Report of the State Mining Engineer, 
the Northampton field is capable of a greatly increased produc- 
tion, but requires more extensive development and organiza- 
tion, and the erection of suitable concentration plants as a 
necessary preliminary to successful operations on a large 
scale. At the present time there appear to be difficulties 
connected with the smelting of the concentrate produced. 
Before the war the ore was chiefly exported to England for 
smelting, this being considered the cheapest method of treat- 
ment, although the Fremantle Trading Company had local 
smelting works. Under present regulations the export of lead 
ore from Australia is prohibited, so that a local solution of 
the problem becomes necessary, and it has been proposed 
that a new central smelting establishment should be erected. 



AUSTRALIA 73 

v 

As, however, works already exist at Fremantle which are said 
to be capable of dealing with a greatly increased output, or, 
alternatively, the concentrate could be sent for treatment to 
the smelters in the eastern States, at Port Pirie and else- 
where, this proposal has met with opposition. 

According to a recent estimate the value of the lead pro- 
duced in West Australia up to the end of 1918 was 963,880 

[40]- 

Tasmania. There are several important lead-zinc deposits 
known in this island, but the output of ore has been irregular 
owing, it is said, to the intermittent working of the Zeehan 
smelters. The chief deposits are situated on the west side 
of the island in the Read-Rosebery district; others of im- 
portance are near Zeehan and at Waratah. 

The Read-Rosebery ore-field has been proved over an area 
seven miles in length, extending from Mount Black on the 
north to Mount Read on the south. This region was formerly 
chiefly a copper producer. The country rock consists mainly 
of mica schist, with bands of limestone, slate, sandstone and 
quartzite, and intrusions of diorite. The ore bodies exhibit 
a banded structure, different bands being characterized by 
the predominance of a particular ore. The metallic con- 
stituents are blende, galena, pyrite and chalcopyrite. The 
galena is argentiferous, and some gold is present also. The 
gangue minerals, which are quite subordinate, comprise 
quartz, calcite, barytes, rhodochrosite, sMerite and chlorite. 
The vertical extent of the ore so far observed is 2,700 ft. 

In the Mount Read group of deposits [41] the chief under- 
takings are the Mount Read, Hercules, Ring P. A., and Jupiter 
Mines. The average compositions of the ores from the Her- 
cules Mine, which has been so far the largest producer, are as 
follow : 





Zinc. 


Lead. 


Copper. 


Silver. 


Gold. 




Per cent. 


Per cent. 


Per cent. 


Ounces 
per ton. 


Ounces 
per ton. 


Gossan .... 
Lead ore . 
Zinc ore . 
Copper ore 


28-0 
40-8 


9-47 
9-35 
7-0 


4'4 


21-9 
12-7 
9-7 

2-O 


0-50 
O-2O 
0-157 



74 SOURCES OF SUPPLY OF LEAD ORES 

It is estimated that the reserves of zinc-lead ore in this 
mine total over half a million tons. 

Operations on these deposits were extended in 1900, from 
which date up to 1914 about 200,000 tons of zinc-lead ore and 
2,500 tons of copper ore, having a total value of approxi- 
mately 300,000, 'were produced. 

The deposits of the Rosebery area [42] are worked by three 
companies, namely, the Tasmanian Copper Co., the North 
Tasmanian Copper Co., "and the Primrose Mining Co. The ore 
of this district is said to have the following average composi- 
tion : blende 43-3 per cent., pyrite 31 per cent., galena 10-4 
per cent., chalcopyrite 1-2 per cent., tetrahedrite o-i per 
cent. ; with 10 oz. of silver and 3 dwt. of gold to the ton. 
Operations are conducted at the Rosebery Mine, on the western 
slope of Mount Black, where several large and well-defined 
lodes have been opened up. Other properties are the Koonya 
and the Dalmeny Mines, in the former of which a considerable 
body of ore has been located. 

The output of zinc-lead ore in this area during 1915 was 
96,890 tons, in addition to which there were said to be over 
200,000 tons of ore blocked out. 

The Mount Lyell Co. have recently acquired the chief mines 
of the Read-Rosebery district and propose to treat the com- 
plex ore electrolytically. 

Full particulars of the operations in this district will be 
found in the monograph on Zinc Ores in this series (pp. 19-23) . 

In the Zeehan district [43], where tin ore also occurs, lead- 
bearing veins and irregular deposits, from 60 to 200 ft. wide, 
occur in Lower Palaeozoic rocks, in connection with granite. 
The region exhibits an interesting series of transitional types, 
ranging from tin veins in the granite to the copper-, lead- 
and zinc- bearing veins in the surrounding rocks, and the ores 
show considerable overlapping in their occurrence. Thus, in 
the lead-bearing veins the galena is sometimes associated 
with tin ore, and the occurrence of an argentiferous sulphide 
of tin is interesting. Compounds of antimony and sulphide 
of bismuth occur. The galena is highly argentiferous, the 
ore in certain cases containing as much as 200 oz. of silver to 
the ton. The upper parts of the veins carry oxidized lead 



AUSTRALIA 75 

ores, together with native silver, silver chlorides, and silver 
sulphides. 

Similar ore-bodies exist in the Dundas region, east of Zeehan, 
but so far these deposits have not been an important source 
of lead. Lead ore, in association with zinc ore, has been 
prospected and opened up in several places at McLean's Creek, 
on the west coast near Zeehan, and there are one or two 
mines at work, though hitherto the production has been small. 

The mines of the Waratah district operate upon lodes 
carrying argentiferous galena associated with blende. 

Australian Exports 

Recent exports of pig lead, matte, silver ore and silver-lead 
concentrate are shown in Tables XIII, XIV and XV. 



NEW ZEALAND 

Although lead ores occur in several localities in New Zea- 
land, so far little has been done to develop them commercially. 
In many cases lead is found as a subsidiary metal in gold and 
silver deposits. 

The Hauraki Peninsula, in North Island, is extensively 
mineralized and contains an assemblage of veins connected 
with Tertiary volcanic rocks. Several of these deposits have 
been worked for gold with highly successful results, as in the 
Waihi and other mines, but there are many in which the pro- 
portion of base metals is high, and the district appears to 
contain large reserves of lead and zinc ores which merit 
attention. 

Further particulars will be found in the Imperial Institute 
monograph on Zinc Ores (pp. 24-26). 



7 6 



SOURCES OF SUPPLY OF LEAD ORES 





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Netherlands 
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CO 

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Total lead in ore 


Lead in concent! 


o 



CHAPTER III 
SOURCES OF SUPPLY OF LEAD ORES (continued) 

(b) FOREIGN COUNTRIES 
EUROPE 

MANY large and important deposits carrying lead and zinc 
ores occur in Europe, and several have been worked for very 
long periods. With the deepening of the mines and the 
opening up of the lower zones, however, many of the deposits 
have become sources of zinc rather than of lead. Very many 
have been abandoned. 

AUSTRIA 

The largest deposits in this country are found in Carinthia. 
They occur in Triassic limestones and dolomites, and extend 
over an area nearly 100 miles long and several miles wide. 
The ores occur in flats, gash veins, and irregular deposits as 
fillings and replacements, and are closely connected with the 
faulting and jointing of the beds in which they are found. 
The mineralization is quite independent of igneous activity 
and has a close resemblance to that of Missouri, described 
later. The best known mining districts are those of Raibl 
and Bleiberg. 

Although these deposits have yielded large quantities of 
lead ore, in the form of gal.ena and cerussite, they are now 
noted more especially for their yield of zinc, and the ores pro- 
duced are chiefly calamine and blende. Hemimorphite and 
hydrozincite occur in small quantities. The occurrence of 
large quantities of wulfenite has been a notable feature. 
Marcasite, pyrite and chalcopyrite accompany the ores, and 

78 



AUSTRIA 



79 



the common gangue minerals are calcite and barytes, though 
these are often practically absent. 

The well-known deposits north of Graz, in Styria, consist 
of veins carrying galena, with 0-06 per cent, of silver, and 
blende, together with sulphides of copper and iron. The vein 
accompaniments are quartz, barytes, witherite and carbon- 
ates of iron and lime. 

Some pre-war imports of dressed lead ore into Austria- 
Hungary are shown in Table XVI. 

Table XVI 

Imports of Dressed Lead Ore into Austria-Hungary * 
In metric tons (2,204 H>-) 





1910. 


1911. 


1912. 


1913- 


From British countries : 










Australia ..... 


4,001 f 





1,980 


6 -54 


From foreign countries : 










Germany 


140 


1 80 


298 


45 


Russia 


146 


497 


59 




Serbia 


1.394 


15 







Tunis . 
United States 


674 


508 


902 
I 


1,915 
41 


Totals (foreign countries) . 


2.354 


1,200 


1,260 


2,001 


Grand totals .... 


6,355 


1,200 


3-24 


8,055 



* Statistik des A uswartigen Handels des Vertragszollgbeites der beiden staalen 
der Oslerr-Ungar Monarchic. 
t Including 235 tons from United Kingdom. 



BELGIUM 

The well-known deposit of the Moresnet district [44] extends 
from Belgium into Luxembourg and Prussia, and is worked 
in the celebrated Vieille Montagne Mine, which has been 
responsible for a very large output of zinc ore. 

The ore-bodies occur in Carboniferous limestone and pre- 
sent many similarities to those of Missouri. They show no 
association with any igneous rocks, but are clearly dependent 
upon a set of fractures trending north-west and south-east. 



8o 



SOURCES OF SUPPLY OF LEAD ORES 



The ores occur as replacement deposits of the limestone, 
which has been extensively dolomitized, and are found chiefly 
along the contacts of shale beds, but also occupy fault fissures. 
Galena and blende, which are often intimately intergrown, 
occur only in depth, and so far no great quantities have been 
proved. The ores at present developed are chiefly carbon- 
ates, and enormous masses of calamine, occurring near the 
surface, have furnished a large production of zinc, though the 
output at the present time is small. 

At Bleyberg, veins carrying lead and zinc ores occur in 
Carboniferous limestone and overlying coal measure shales, 
and have been extensively mined. Other occurrences of lead 
ore in Belgium are those near Liege and Verviers. 

Belgium's production of lead for recent years is shown in 
Table II, p. 38, and also her imports of crude lead and her 
exports of manufactured lead are shown in Tables XVII and 
XVIII. The case of Belgium is peculiar inasmuch as although 
her domestic production is small she shows considerable 
exports, a fact due to her position as a halfway-house, 
with a large re-export trade. She was further the possessor 
of an important metallurgical industry, and it will be noticed 
in Table XVIII that a certain amount of lead was exported 
in the form of beaten, rolled or drawn metal. 

Table XVII 
Imports oj Crude Lead into Belgium 

In metric tons (2,204 Ib.) 



From 


1910. 


1911. 


1912. 


1913. 


Australia . 


1,505 


1,550 


2,595 


1.896 


United Kingdom 


1,423 


2,526 


1,464 


2,441 


Germany 


i,344 


2,244 


1,564 


3,238 


Greece 


8,649 


5.499 


680 


12,054 


Hamburg 


2,533 


1,464 


2,414 


190 


Mexico 


11,668 


17,497 


14,095 


5,799 


Spain 


15,818 


40,3" 


33,162 


3L528 


Turkey 


7,422 


3.930 


5,126 


6,081 


United States 


1,908 


3,672 


2,636 


2,543 


Other countries 


1,598 


4,809 


4,303 


6,422 


Totals 


53,868 


83,502 


68,039 


72,192 



BELGIUM 



81 



Table XVIII 

Exports oj Lead from Belgium 

(Crude metal, and beaten, rolled or drawn) 

In metric tons (2,204 M>-) 






1910. 


1911. 


i')i-. 


1913. 


United Kingdom 


4.030 


3.044 


6.143 


10,151 


France 


30,389 


35.306 


35.773 


47.656 


Germany . 


15,216 


23.3" 


18,720 


14.284 


Netherlands 


4.354 


4.035 


3.i5t 


4.584 


Russia 


7-447 


7.351 


8.857 


6,586 


Other countries 


4.37 


4.915 


5,879 


3.970 


Totals 


65,806 


77.902 


78,523 


87.231 



BULGARIA 

The Blagodat Mine, near Kustendil, has yielded ore con- 
taining 15 per cent, of lead and 25 per cent, of zinc. Deposits 
carrying lead and zinc are mined in several other places in 
Bulgaria, as at Sedmolchisleniza and Roupio, but the output 
of lead is small. 

CZECHO- SLOVAKIA 

There are several places in Bohemia where lead is or has 
been mined, the most important occurrences being those of 
Przibram, near Prague [45]. These mines have been worked 
for several hundred years and the deposits followed to depths 
of between 3,000 and 4,000 ft, but the output is now small. 
The veins, of which about forty have been worked, are con- 
tained within a narrow area, four or five miles hi length, and 
occupy a series of folded and faulted Lower Palaeozoic sedi- 
ments, intruded by diorite and dykes of greenstone. A large 
fault, the Lettenkluft, traverses the district, bringing shales 
against grits, and where the lodes cross this junction they 
become impoverished in the shales. The richest ore occurs 
where the lodes cross the greenstone dykes. 

The ores comprise galena and blende, with pyrite and 
chalcopyrite, and occasionally compounds of arsenic, anti- 
mony, uranium, cobalt and nickel. The galena is argen- 



82 SOURCES OF SUPPLY OF LEAD ORES 

tiferous, containing up to -5 per cent, of silver, and rich silver 
minerals, such as argentite, pyrargyrite, and native silver, 
were abundant in the oxidized zone. Calcite, siderite and 
quartz are the predominant gangue minerals, barytes being 
uncommon. The proportion of blende increased with depth. 

Lodes carrying lead and zinc ores have been worked near 
Pilsen, and it is noticeable that in certain of the veins, in 
which the gangue is calcite and dolomite, the proportion of 
silver in the galena is higher than it is in others in which the 
gangue is barytes and fluorspar. 

At Kuttenberg, east of Prague, and at Budweis, in Southern 
Bohemia, veins containing galena and blende, together with 
ores of silver, occur in gneiss. 

The occurrences in North-western Bohemia are an extension 
of the deposits of the Saxon Erzegebirge, considered later, 
(p. 86). 

FRANCE 

Lead ores occur at many places in France, the chief deposits 
being situated in the metamorphic and associated igneous 
rocks of the Auvergne, in the Jurassic limestones and other 
rocks to the south and south-west of that region, in the 
Pyrenees, in the Alpine district of Provence, and in Brittany. 

The deposits of the Auvergne district are found principally 
in the Departments of Puy-de-D6me, Cantal, and Haute- 
Loire. The veins occur in gneiss and other metamorphic 
rocks, invaded by veins of fine-grained granite and quartz 
porphyry, and are contemporaneous with the older Tertiary 
volcanic rocks. The ores comprise argentiferous galena and 
blende, with pyrite, chalcopyrite, and compounds of antimony. 
Quartz is the chief gangue mineral, calcite and barytes being 
less frequent. The principal mines are situated at Pontgibaud. 

In the Departments of Gard, Lozere and Lot, to the south 
of the Auvergne, the ores occur in limestones and dolomites 
of Jurassic age, and in granite and metamorphic rocks, as 
constituents of veins, some of which reach large dimensions, 
and as metasomatic replacements. The ores consist of galena 
and blende, with anglesite, pyromorphite, calamine, and 
hydrozincite as secondary products, while barytes is an im- 



FRANCE 







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SOURCES OF SUPPLY OF LEAD ORES 



portant constituent in some cases. The chief mining localities 
are Malines, Bleymard, Vialas and Planioles. _Similar deposits 
are found near Angouleme, in Charente. 

In the Pyrenees lead ores are found in the Departments of 
Ariege, Hautes Pyrenees, and Basses Pyrenees. At the well- 
known mines of Boulard de Sentein St. Lary, and at Girons, 
in Ariege, the deposits occur in Carboniferous limestone and 
yield argentiferous sulphides and carbonates of lead and zinc. 

The deposits of Provence occur in the Department of Var, 
and consist of lodes traversing schists and quartzites. The 
vein contents, however, carry very little galena, and the chief 
ores are blende and its secondary products. 

The best known occurrence in Brittany is that of Pontpean, 
near Rennes, in the Department of Ille-et-Vilaine. The vein 
worked occurs in metamorphosed Silurian rocks and carries 
argentiferous galena and blende. 

Some details of the import trade of France in lead and lead 
ore are given in Tables XIX, XX and XXI. 

Table XXI 
Imports oj Dressed Lead Ore into France * 

In metric tons (2,204 lb.) 





1912. 


1913. 


1914. 


1915- 


1916. 


1917. 


From British countries : 
Australia . 


6.043 





2,914 





55 





From foreign countries : 
Algeria 
Austria-Hungary 
Belgium 
Italy . 
Spain 
Tunis 
Other foreign countries 


15,886 

880 
11,677 
1,562 

5,526 
880 


17,813 
2,088 
1,213 

i3,95i 
1,908 

2.378 
421 


5,928 

411 
11,807 
543 

177 


9,541 

282 
6,164 
133 


21,173 

9,871 
1,363 
7,736 

IO2 


18,615 

3,915 
82 4 
11,967 
706 


Totals (foreign coun- 
tries) . . . 


36,411. 


39,772 


18,866 


16,120 


40,245 


35,027 


Grand totals . 


42-454 


39,772 


21,780 


16,120 


40,750 


35,027 



According to Doci4tnents Statistiques . . . sur It Commerce de la France, 
1918, the total imports for the years 1916, 1917, 1918 and 1919 were 40,750, 
36,027, 20,335 and 11,968 tons respectively. 

* Tableau General du Commerce el de la Navigation. 



GERMANY 85 

GERMANY 

This country has occupied a foremost place as a producer 
of lead ore, her annual output having been over 300,000 tons. 
This quantity, however, was insufficient to satisfy her large 
smelting industry, and her imports of ore were very con- 
siderable, the annual amount exceeding 100,000 tons. By far 
the most productive deposits have been those of Upper Silesia 
(to be subject to plebiscite), the output of ore from these mines 
being more than half the country's total production, while 
that of zinc ore was even greater (see p. 96). 

Other deposits occur in Saxony, the Harz Mountains, 
Nassau, Westphalia, near Aix-la-Chapelle, and in the Black 
Forest, but many of them are now practically exhausted so 
far as lead is concerned. 

The chief occurrences of lead ore in Saxony are in the neigh- 
bourhood of Freiberg. These well-known silver-lead deposits 
belong to a complicated system of fissure veins, varying in 
character and age, which are contained in biotite gneiss and 
other metamorphic rocks. They are most probably genetically 
connected with the post- Carboniferous granites of the Erzege- 
birge, and represent a higher portion of the same mineraliza- 
tion as that to which the celebrated tin- bearing veins belong. 
The mining activity of this district extends over a period of 
between 700 and 800 years, but operations have now prac- 
tically ceased. Depths of over 2,000 ft. have been attained 
in the workings. 

The deposits have been the object of repeated study by 
many geologists and there is an extensive literature relating 
to them [46]. The veins have been classified into a number 
of types, which are grouped into an older and a younger series. 
To the former, which includes also the rich silver- quartz veins 
of the district (noble quartz formation) and the tin veins of 
the Erzegebirge, belong the pyritic lead veins and the rich 
silver-lead veins (noble lead formation) ; the latter comprises 
the barytes-lead veins. The pyritic lead veins carry argen- 
tiferous galena, blende and pyrite, with pyrrhotine, mispickel, 
and chalcopyrite, in a gangue of quartz ; while in the silver- 
lead veins the galena, which is highly argentiferous, is accom- 



86 SOURCES OF SUPPLY OF LEAD ORES 

panied by sulpho-salts of silver in a gangue composed chiefly 
of ankerite and rhodochrosite. In the younger barytes-lead 
veins, which often are of considerable width, the galena is 
much poorer in silver and the gangue is composed of barytes, 
fluorspar, calcite and quartz ; these veins sometimes carry 
cobalt and nickel minerals. 

South of Freiberg, in the celebrated mining region of the 
Erzegebirge, which extends into Bohemia, some of the veins 
carry argentiferous galena and blende, as at Altenberg, Schnee- 
berg, and other places, but the ores are usually dominated by 
the presence of chalcopyrite and mispickel, and are quite 
unimportant in comparison with those of tin, copper, silver 
and cobalt, for which this district is famous. 

Many lead deposits, which have been extensively worked, 
occur in the region of the Harz Mountains, the most impor- 
tant being the numerous veins of the Clausthal Plateau, which 
have been mined since the thirteenth century [47] [48]. The 
veins, which have an average trend to the west-south-west, for 
the most part occupy faults in a folded complex of Devonian 
and Carboniferous sediments, and form a system of more or less 
parallel fissures linked together by numerous branches. They 
extend over an area fifteen miles in length and five miles in 
width. The main veins are composite and of considerable 
widths. They form ten parallel series of lodes which have 
been traced along the strike through practically the whole 
mineral area. The deposits have been mined to depths of 
3,000 ft. 

The chief ore is galena, but blende preponderates locally 
and increases with depth. Marcasite, pyrite, chalcopyrite 
and tetrahedrite occur also, and interesting rarities are the 
selenides of lead and copper. The gangue minerals comprise 
quartz, calcite, barytes and siderite, the latter two being 
limited to certain veins in the south. 

The silver content of the galena is generally low, averaging 
from -oi to -05 per cent., but is sometimes as much as -3 per 
cent. 

On the northern slopes of the Harz Mountains, near Goslar, 
is the large deposit of Rammelsberg which has been worked 
for copper ores since the tenth century. This deposit, how- 



GERMANY 87 

ever, is of small importance as a source of lead though it has 
produced considerable quantities of zinc ore. The ore-bed, 
as it is called, is contained within a deformed series of Devonian 
slates, with which it is more or less conformable, and dips at 
a steep angle to the north. Its thickness varies considerably, 
but is usually about 10 ft., though in places it may swell to 
as much as 40 yards ; its limits are generally sharply denned. 
The origin of this ore-body has been the subject of much 
controversy [49]. 

The ores, in their order of importance, are blende, chalcopy- 
rite, galena, pyrite and mispickel, and they occur in intimate 
admixture. Barytes constitutes about the only gangue, but 
is seldom present in quantity. The zinc concentrate obtained 
carries 12 per cent, of lead, in addition to 25 per cent, of zinc. 
Galena occurs hi the lodes of St. Andreasberg, to the south 
of the Harz Mountains, noted for their rich silver ores, but 
the mining of these deposits, which reached a depth of nearly 
3,000 ft., ceased in 1910. 

In Nassau, two well-known deposits occurring in the Valley 
of the Lahn have been extensively mined. These are known 
respectively as the Ems and Holzappel veins, and consist of 
two zones of fissuring traversing Lower Devonian slates. The 
Ems series of veins, which extends from Braubach to Deer- 
bach in an easterly and westerly direction, carries argen- 
tiferous galena, blende, chalcopyrite and -pyrite in a gangue 
of siderite, calcite and quartz. Below the gossan there 
occurred a zone containing tetrahedrite and sulph- arsenides of 
nickel and cobalt. The complex ore is said to contain 4 per 
cent, lead, 2-5 per cent, zinc, and 2 oz. of silver per ton, and 
to yield (i) lead concentrate carrying 36 per cent, lead, and 
ii oz. of silver per ton, and (2) zinc concentrate containing 
44 per cent. zinc. 

The Holzappel series of veins extends for a distance of 
nearly eight miles from St. Goar to Holzappel, and contains 
an assemblage of minerals similar to that of the Ems veins. 
A characteristic feature is the brecciated nature of the vein- 
stones, in which the sulphides act as a cement. 

The lead deposits of Westphalia comprise both veins in the 
Palaeozoic slates and metasomatic replacements in limestone. 
7 



88 SOURCES OF SUPPLY OF LEAD ORES 

The former occur in the neighbourhoods of Coblenz, Arnsberg, 
Gladbach, Dusseldorf, etc , and present the usual types. Those 
of Coblenz have features in common with the Holzappel veins. 

The metasomatic deposits are found in the Stringocephalus 
limestone of Middle Devonian age, the best-known occurrences 
being in the districts of Iserlohn and Brilon. The ore-bodies 
occur as irregular masses in the limestone, more especially 
at its junction with the underlying Lenne Slates. The ores 
comprise galena and blende, with their oxidation products, 
and there is a noteworthy amount of pyrite. 

At Commern and Mechernich, near Aix-la-Chapelle, lead 
ore occurs as a dissemination in Triassic sandstone. The 
deposit, which is worked in open cuts, is of low grade, 
averaging 1-5 per cent. lead. The ore bed is about 65 ft. thick 
and occurs about 130 ft. below the surface. The ores are 
galena and cerussite, with a little chalcopyrite. Barytes 
occurs, generally filling small veins and fissures in the sand- 
stone. The occurrence of the galena in small lumps or con- 
cretions dispersed through the sandstone has given rise to the 
name of Knotenerz, by which it is locally known. The mining 
of these deposits dates back for several hundred years, but 
is of little importance at the present day. 

Similar deposits are found in other parts of Germany. In 
Bavaria and Wiirtemberg, gypsum-bearing beds belonging 
to the Upper Trias (Keuper) contain galena and chalcopyrite 
associated with blende and barytes. The Voltzia Sandstone, 
of Bunter age, has been worked in places in Rhenish Prussia 
and Lorraine for lead and copper ores, the minerals being 
cerussite, galena, chalcocite and copper carbonates. 

The Kinzig Valley, in the Black Forest (Baden), contains 
an assemblage of veins of varied composition and age. They 
are contained principally in the older, gneissic, rocks, but 
also extend into the overlying Triassic and Permian sand- 
stones. The veins have been classified into a number of 
types, grouped in two series, to the younger of which belong 
those carrying argentiferous galena. The district has yielded 
also ores of silver, cobalt and antimony. 

At Munsterthal, in the same region, the lodes, which are in 
biotite-gneiss, carry galena and blende with subordinate 






GERMANY 89 

amounts of pyrite and ores of silver, antimony and arsenic. 
The gangue minerals are quartz, fluorspar, calcite, siderite 
and barytes. In the Schapbach region the deposits are similar. 

At Wiesloch are metasomatic replacements in limestone, 
but these are of more importance as a source of zinc than of 
lead. 

Germany, although a large producer of lead ore, also im- 
ported considerable quantities, a fact due to her big consump- 
tion. Her exports of lead, partly in a manufactured form, 
were round about 40,000 tons annually, a figure about half 
that of her imports of the metal, so that she was to a large 
extent dependent upon foreign supplies. A large portion of 
her imported lead ore came from Australia. 

Details of some pre-war exports of crude and manufactured 
lead, and of imports of dressed ore and crude lead are given 
in Tables XXII-XXV. 

Table XXII 

Exports of Lead jrom Germany * 

Rolled (sheet lead, etc.) 

In metric tons (2,204 lb-) 





1910. 


1911. 


1913. 


1913. 


To British countries : 
United Kingdom 


1,232 


1.504 


2.583 


2,041 


To foreign countries : 
Netherlands 
Roumania 
Russia . 
Sweden 
Switzerland 
Other foreign countries 


1,007 
116 

497 
163 
405 
1,262 


932 
187 
86 1 
331 
45 
1.334 


56i 

253 
486 
280 
354 
1.332 


611 
644 

416 
1,920 


Totals (foreign countries) 


3.450 


4.050 


3,266 


3.591 


Grand totals 


4,682 


5.554 


5.849 


5.63a 



* Staiistik des Deutschen Reichs Band 260, 77. 



SOURCES OF SUPPLY OF LEAD ORES 



Table XXIII 

Exports of Lead from Germany * 

Crude (in blocks, pig, etc.) 

In metric tons (2,204 It)-) 





1910. 


1911. 


1912. 


1913- 


To British countries : 
United Kingdom 


823 


1,260 


1,119 


1,298 


To foreign countries : 
Austria-Hungary 
Belgium 
France . 
Netherlands 
Russia . 
- Switzerland 
Other foreign countries 


12,026 
990 
1,916 
1,941 
8,352 
3,i54 
i,795 


13,063 

2,387 
246 

3,295 
6,767 
2,877 
2,369 


18,150 
2,231 
483 
3,564 
6,468 
3,207 
2,900 


14,661 

6,497 
3,352 
1,883 

7,487 
3,n6 

3,075 


Totals (foreign countries) 


30,174 


31,004 


37,003 


40,071 


Grand totals 


30,997 


32,264 


38,122 


4L369 



* Staiistili des Deutschen Reichs Band 260, //. 

Table XXIV 

Imports of Dressed Lead Ore into Germany * 
In metric tons (2,204 Ib.) 





1910. 


1911. 


1912. 


1913. 


From British countries : 










Australia 


93,4 8 i 


124,819 


98,252 


127,021 


British South Africa 





99 


307 





United Kingdom 


73 


807 


811 


271 


Totals (British countries) 


93,554 


I25,7 2 5 


99,370 


127,292 


From foreign countries ! 










Austria-Hungary 


6,771 


6,163 


9,337 


2,045 


Belgium 


1,659 


1,500 


970 


497 


China 


263 


1,321 


3,596 


1,279 


France 


3,100 


3,008 


435 




South- West Protectorate 





44 


1,466 


913 


Peru 


1,274 


1,748 


2,563 


2,n8 


. Russia 


1,489 


2,412 


2,639 


2,702 


Spain 


1,120 


467 


422 




Other foreign countries 


2,921 


1,210 


2,029 


6,151 


Totals (foreign countries) 


i8,597 


17,873 


23.477 


15.705 


Grand totals 


112,151 


143,598 


122,847 


142,997 






* Statistik des Deutschen Reichs Band 260, II. 



GERMANY 

Table XXV 

Imports of Lead into Germany * 
Crude (in blocks, pig, etc.) 
In metric tons (2,204 lb.) 





1910. 


1911. 


1912. 


1913. 


From British countries : 
Australia 
United Kingdom 


8,791 
4,184 


6,697 
6,135 


4.103 
3,721 


2,839 
3.923 


Totals (British countries) 


12.975 


12,832 


7.824 


6,762 


From foreign countries : 
Belgium 
Italy 
Mexico . 
Netherlands 
Spain 
Sweden . 
United States 
Other foreign countries 


29,063 

5 
2,320 

5M 
13.917 
535 
20,331 
1,882 


33.798 
3 
3,3i4 
746 
11,788 
517 
35, 8 43 
1,699 


33.165 
757 
1,104 
1,266 
24,37 

1,022 
22,928 
I.I49 


13.973 
873 
2O 

835 
42.793 
680 
16,273 

1.554 


Totals (foreign countries) 


68,566 


87.708 


85.761 


77,019 


Grand totals 


8i,54i 


100,540 


93.585 


83.781 



* Statistik des Deutschen Reichs Band 260, //. 



GREECE 

There are many localities in this country where lead and 
zinc ores occur as metasomatic replacements in limestone, 
the largest and best- known deposits being those of Laurium, 
south-east of Athens, which have been mined from early times. 

According to Hofman [4/p.i] the silver- lead mines of 
Laurium " were in operation before 560 B.C. ; they flourished 
100 years later, and were considered to be worked out at the 
beginning of our era. In 1863 they were reopened by a 
French company which erected smelting works and treated 
new ores, and the ancient concentration- and slag-dumps ; 
the works are in operation at present." 

The ores are contained in low-dipping beds of limestone, 
separated from one another by interstratifications of shale, 
and the ore-bodies occur chiefly along the contacts, forming 
a series of parallel layers, varying in thickness from 2 to 40 



92 SOURCES OF SUPPLY OF LEAD ORES 

ft. and traceable for distances of upwards of a mile. There 
are three main horizons. 

The primary ores consist of argentiferous galena and blende, 
in a gangue of siderite, while in the upper parts of the 
deposits occur cerussite, calamine, haematite and gypsum. 
Of great interest are the oxychlorides of lead which have been 
formed by the action of the sea water on the ancient slag 
heaps. 

Argentiferous lead ores have long been worked in the islands 
of Milos, Pharos and Santorin, in the ^Egean Sea. The 
deposits are associated with volcanic rocks, and carry, in 
addition to galena, blende, chalcopyrite and pyrite, with 
frequently barytes as a gangue. 

HUNGARY 

In the region of the Carpathian Mountains occurs an extensive 
series of Tertiary volcanic rocks with which are associated an 
interesting assemblage of mineral veins. These veins are 
notable for the great variety of minerals occurring in them, 
including gold tellurides, rich silver ores, galena, blende, pyrite, 
marcasite, chalcopyrite, tetrahedrite, bournonite, jamesonite, 
stibnite and cinnabar, while the gangue minerals comprise 
calcite and other carbonates, barytes, zeolites, and fluor- 
spar. The various minerals, however, are subject to local 
distribution. 

The most important ores are those of gold and silver, but in 
certain veins galena preponderates. 

The chief mining districts are those of Schemnitz-Kremnitz, 
Nagybanya-Felsobanya-Kapnik and the Transylvanian Erze- 
gebirge. Mining operations are extremely old and date from 
the eleventh century or before. The industry was flourishing 
about the sixteenth_century. A large number of the mines 
are state-owned. 

In the Schemnitz-Kremnitz district the Johann and Spitaler 
lodes are chiefly galena-bearing, and have been mined for that 
ore. Secondary minerals, such as cerussite and pyromorphite, 
were present in large amount. 

The chief lead occurrences of the Nagybanya-Felsobanya- 



HUNGARY 93 

Kapnik district are at the last-named places, more especially 
Kapnik. The galena, which is often accompanied by blende, 
is richly argentiferous. 

The district of the Transylvanian Erzegebirge is noted 
especially for its gold tellurides, and ores of lead are quite 
subordinate. The mines of this area are drained by the 
celebrated Franz-Joseph adit, which has a length of 5,012 
metres. 

ITALY 

The chief deposits are situated in Sardinia. Others are 
found in Tuscany, Lombardy and Piedmont. 

In the neighbourhood of Iglesais, in Southern Sardinia, 
there are numerous occurrences of lead ore, both in lodes 
traversing granite and metamorphic Cambrian and Silurian 
strata, and as large replacements in dolomitic limestones of 
Orodovician age. The deposits are mined principally at 
Montevecchio, Monteponi, Malfatano, and other places. 

At Montevecchio the veins, which vary in width from mere 
stringers up to lodes 50 to 100 ft. wide, carry argentiferous 
galena, with 0-08 to 0-17 per cent, of silver, and blende, with 
sulphides of copper and iron. The secondary ores comprise 
cerussite, pyromorphite, crocoisite, and carbonate of iron, 
together with native silver, ruby silver, and horn silver. 
Cinnabar and compounds of arsenic, antimony, nickel and 
cobalt occur also. The gangue minerals are principally quartz 
and calcite, but barytes, fluorspar and zeolites are found. 
Where the veins are associated with limestone there is an 
extensive metasomatic replacement of the country rock, and 
a predominance of zinc in the form of calamine and blende." 

At Monteponi [50] the deposits consist of large irregular 
replacements in limestone, occurring chiefly along normal or 
faulted contacts with slates. The primary ores are galena 
and blende, the former occurring more particularly in the 
upper zones. Near the surface there are large deposits of 
the secondary zinc ores, calamine and hemimorphite. 
Similar ore-bodies occur at Malfatano, and the district is now 
of more importance as a source of zinc than of lead, being, in 
fact, one of the most productive zinc regions in Europe. 



94 SOURCES OF SUPPLY OF LEAD ORES 

It is known that the " Romans worked lead mines in Sar- 
dinia which had been opened up by the Phoenicians and 
operated by the Carthaginians " [4/p. 2]. 

In the Campiglia Marittima district of Tuscany the lodes 
occur in Palaeozoic slates and carry argentiferous galena, con- 
taining from 0-3 to 0-5 per cent, of silver, blende, chalcopyrite, 
and antimonial lead ores, together with small quantities of 
cassiterite and compounds of cobalt and bismuth, in a gangue 
of quartz, calcite and siderite. The deposits are mined at 
Bottino. 

Near Trent, and at other places in the Tyrol, occur many 
well-known lead and zinc veins, in which the galena is often 
highly argentiferous. At Pfundererberg the galena carries 
from 0-3 to 0-6 per cent, of silver, and the associated sul- 
phides of copper and iron are auriferous. 

Recent imports of crude lead into Italy are given in 
Table XXVI. 

Table XXVI 

Imports of Pig Lead into Italy * 
In metric tons (2,204 M>.) 





1912. 


1913. 


1914. 


1915. 


1916. 


1917. 


1918. 


1919. 


Australia . 


















United Kingdom 


717 


283 


876 


189 


152 


377 


74 


119 


France 


1,816 


126 


155 


I 


406 


226 







Spain 


12,661 


10,316 


7,413 


12,227 


II,96O 


21,081 


6,567 


6,132 


United States . 





26 


155 


4.340 


763 


4.519 


269 


211 


Other countries 


433 


743 


1,221 


569 


1,077 


76 


5,546 


5,759 


Totals 


15,627 


H.494 


9,820 


17.326 


14,358 


26,279 


12,456 


12,221 



Minister*) del Finanze. Statistica del Commercio Specials. 

NORWAY 

Lead ores occur near Vefsen and at other places in Norway, 
but so far the deposits have not been extensively exploited. 
The lodes occur in gneisses, schists, and Palaeozoic rocks in 
association with gabbro and granite, and carry argentiferous 
galena, with from 0-2 to 0-8 per cent, of silver, and blende, 
together with silver ores and sulphides of iron, copper and 
antimony. 



POLAND PORTUGAL RUSSIA SPAIN 95 

POLAND 

The deposits of Poland, which were formerly more exten- 
sively mined than at present, are an extension of those in 
Upper Silesia, considered, below. They have been mined 
chiefly at Boleslaw, Szakowa, Trzebinia and Olkusz, but the 
occurrences are less important than those of Germany. 

PORTUGAL 

This country is not an important producer of lead ore 
though several deposits are known. In Oporto, lodes contain- 
ing argentiferous galena form part of a series of veins in 
which cassiterite, wolfram, and ores of antimony occur, but 
the deposits are not at present a source of lead. 

RUSSIA 

Lead ores have been mined in the Caucasus and in Siberia, 
but detailed accounts of the deposits are not easily obtained. 
A large deposit carrying galena and blende is being worked at 
the Ridder Mine in the Semipalatinsk district of South-western 
Siberia. The ore-body is estimated to contain nearly a 
million tons of high-grade sulphide ore, and about 2,500,000 
tons of low-grade ore. 

SPAIN 

This country, formerly the largest producer of ore in Europe, 
ranked only second to the United States in the world's 
production. The chief deposits are near Linares, in the 
Sierra Morena, and at Ciudad Real, to the north of that region. 
Others are those in the Province of Murcia, in the south-east ; 
north of Almeria, in Granada ; and in the Guadalajara dis- 
trict, north-east of Madrid. The metasomatic deposits of 
Santander, in the north, are essentially sources of zinc. 

At Linares the lodes traverse granite and Silurian slates 
and quartzites. The ore is almost exclusively galena, only 
slightly argentiferous, and blende and pyrite are practically 
absent. The principal veinstone is quartz, with small amounts 
of dolomite and occasionally barytes and siderite. Cerussite 



96 SOURCES OF SUPPLY OF LEAD ORES 

occurs in the oxidized zone. Linarite, the basic sulphate of 
lead and copper, is found here. 

At Ciudad Real the deposits are similar, but the galena is 
more argentiferous, containing from 0-4 to 0-5 per cent, of 
silver. 

In the Province of Murcia, around Cartagena and other 
places, there are lodes traversing slates, and metasomatic 
replacement deposits in limestone. The galena is associated 
with blende and pyrite and is richly argentiferous. Ores of 
silver occur, and the gangue minerals are calcite and siderite. 

The lodes in the district north of Almeria, in Southern Spain, 
carry argentiferous galena associated with ores of copper in a 
gangue of barytes, strontianite and siderite. Secondary 
silver ores occur in the upper parts of the veins and have been 
extensively mined. 

Similar deposits occur at Guadalajara in Central Spain, 
where the lodes are in gneiss and schist. The veins carry con- 
siderable quantities of barytes. 

Tables XXVII and XXVIII give recent Spanish exports 

of crude and argentiferous lead. 

/ . 

SWEDEN 

The largest deposit of lead ore worked in Sweden is that of 
Sala, to the north of Stockholm, where the ores occur as meta- 
somatic replacements in a metamorphosed dolomitic limestone 
occurring as lenticles in crystalline schists. The main ore is 
galena, with a high percentage of silver, while blende and 
pyrite are subordinate. 

The well-known deposit near Ammeberg is principally 
characterized by the presence of blende, though a small pro- 
portion of galena is present. The zinc concentrate produced 
carries 3 per cent, of lead. 

UPPER SILESIA 

The well-known and important deposits of Upper Silesia 
[51] [52] occur in the south-eastern corner of the province, on 
the borders of Russia and Austria, and extend across the 



EXPORTS FROM SPAIN 



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98 SOURCES OF SUPPLY OF LEAD ORES 

frontiers into Galicia and Russian Poland. It is said that 
mining in this district dates back to the sixteenth century. 
The principal deposits occur in the neighbourhoods of Tarno- 
witz, Miechowitz, Beuthen, Scharley and Dombrowka. 

The ores occur in a mass of dolomite, about 250 ft. thick, 
belonging to the Muschelkalk division of the Trias, the par- 
ticular ore-bearing horizon being in the upper portion of the 
Lower Muschelkalk, known locally as the Upper Wellenkalk 
or Schaumkalk. These beds form part of a series of Triassic 
and Permian rocks occurring in flat synclines and resting un- 
conformably upon Carboniferous rocks which outcrop around 
them. There are coalfields in the vicinity. 

The ore-bodies are replacements of the dolomite, and occur 
at two horizons about 40 to 60 ft. apart. The lower zone 
often rests upon a bed of pyritic clay. The two zones are 
connected by ore-bearing fissures, but the upper one is subject 
to great irregularity both in position and extent, and is often 
absent. The richest sections of the deposits are associated 
with fault fissures. 

The ores consist of galena, blende, calamine, hemimorphite 
and cerussite, with abundant marcasite, the latter containing 
a little arsenic and traces of nickel. 

The distribution of the ores is subject to much variation, 
and while in some places the deposits may consist almost 
entirely of lead ore, in others they are composed predominantly 
of zinc ore, while mixtures of both are common. On the 
whole, however, it may be taken as a general rule that galena 
and oxidized zinc ore preponderate in the upper zone, while 
blende and marcasite are dominant in the lower. Galena 
occurs more particularly in the neighbourhoods of Tarnowitz 
and Trockenberg. It forms sheet-like bodies, varying from 
a few inches to a foot or more in thickness, and occurs also in 
irregular masses and nests. 

The ores produced from this district are now said to contain, 
on the average, 17 per cent, of zinc and 5 per cent, of lead. 
The galena contains a little silver (-02 to -03 per cent.), and 
traces of copper, antimony and gold have also been detected 
in analyses of furnace products. 

There has been much discussion concerning the genesis of 



UPPER SILESIA 99 

these ores, but they are now generall y attributed to the action 
of ascending hydrothermal solutions, which were responsible 
not only for the deposition of the ores but also for the dolo- 
mitization of the limestone. The district is much faulted, the 
fissures passing down into the underlying Carboniferous rocks, 
so that suitable channels for the ascent of the ore-bearing 
solutions were available. The formation of the oxidized ores 
from the original sulphides was a subsequent process connected 
with the circulation of waters of atmospheric origin. At the 
outcrop of the dolomite occur considerable irregular masses 
of ferruginous secondary zinc ores, calamine and hemimorphite, 
which are of great economic importance and have rendered 
this district famous as a zinc producer. 

YUGOSLAVIA 

Serbia. Lead is being mined at Cerveni Brey and Kosmaj 
in Belgrade, and^lso in the Departments of Podrinji and 
Rudnik [53]. 

Babe is a large lead mine, five miles from the Ralja railway 
station, with which it is connected by a narrow-gauge rail- 
way. In 1916 the Austrians were working the mine, and 
were extracting from it daily one car of picked, and 100 
cars of ordinary ore, which were sent inland to be smelted [54]. 

Bosnia. The lead ores of Bosnia occur in veins associated 
with andesitic lavas, slates and quartzites. The ores consist 
of argentiferous galena, with 0-2 per cent, of silver, and blende, 
with pyrite and compounds of copper and antimony. 

Carniola. At Laibach, in Carniola, ores of lead and zinc, 
accompanied by cinnabar and barytes, occur in fissure breccias 
in Carboniferous sandstones and shales. 

ASIA 
ASIA MINOR 

The principal silver-lead mines in Anatolia are those of 
Balia-Karaidin in Brusa, and Bulgar-Maden in Konia. In 
1913 the output from the former mines amounted to 13,076 
tons of lead [55]. The lodes are numerous and vary in thick- 



loo SOURCES OF SUPPLY OF LEAD ORES 

ness from i ft. up to 35 ft. The ore averages 12 per cent, 
lead and 6i per cent, zinc [56]. The argentiferous galena 
occurs in fissures in augite-andesite near its contact with lime- 
stone (Carboniferous), the fissures being parallel to the con- 
tact zone. Ore occurs in the limestone at points where it 
underlies andesite [57]. The mines were shut down during 
the war. The Bulgar-Maden mines have been worked by the 
peasants for nearly eighty-five years. " The deposits are the 
result of contact action of micro-granulites, which have been 
intruded into the Palaeozoic limestones." The annual yield 
amounts to about 400 tons of lead [55]. Narrow, rich veins of 
argentiferous and auriferous galena occur around Karahissa 
(Sivas). The ore is associated with antimony, while near 
Smyrna lead ores are associated with zinc [57]. At Bulgar- 
Dagh (Konia) argentiferous ore is raised, averaging 75 percent, 
lead. In the vilayet of Aidin, silver-lead mines occur near 
Sokia, which from 1911 to 1913 yielded an average of 14,000 
tons of lead. In Angora, silver-bearing lead ore is found in 
various mines which are State-controlled. At Karalar, Kasta- 
muni, a silver-lead mine was worked for some years before the 
war [57]. Important silver-lead deposits occur at Keban 
Maden (Mamuret), on the Euphrates. 



CHINA 

The largest and foremost lead mine in China is that of 
Shui-ko-shan in Hunan Province, Central China, an interest- 
ing description of which has recently appeared in the Mining 
Magazine [58]. According to this account the mine has been 
worked spasmodically for the past 300 years on primitive 
Chinese lines. It was reorganized by a European company 
about 1902, and a plant designed to handle 100 tons of ore 
daily has been erected. During 1914, 55,087 tons of ore 
were treated, giving 14,420 tons of zinc concentrate and 
4,977 tons of lead concentrate. A large proportion of the ore, 
more than half in fact, is hand-picked, and the old Chinese 
floors are still utilized for the treatment of the fines. 

From 1896 to 1912, inclusive, the mine produced a total of 



CHINA 101 

100,683 tons of zinc concentrate and 41,837 tons of lead 
concentrate. 

The occurrence consists of large irregular ore-bodies of 
blende and galena, with pyrite and chalcopyrite in limestone 
(Carboniferous ?) at and near the contact with syenite, but the 
ore-deposit itself appears to be of metasomatic origin. 

The crude ore is said to contain from 19 to 33 per cent. 
of lead, from 23 to 29 per cent, of zinc, and about 20 oz. of 
silver to the ton. The lead concentrate produced carries 73 
per cent, lead, about 8 per cent, zinc, and 30 oz. of silver per 
ton, while the zinc concentrate carries 30-5 per cent, zinc, 
10-4 per cent, lead, and 5 oz. of silver per ton. 

According to the Mineral Industry for 1917 there are ten 
mines successfully operated by Chinese companies in the pro- 
vince of Hunan. These are Kianghua, Pinghsien, Liangsiang, 
Kueiyang, Liling, Lingwu, Liuyang, Hengyang, Suikouling 
and Chowkiagang. 

In the province of Chi-li veins carrying lead and zinc ores, 
in association with rich silver minerals and compounds of 
arsenic, have been mined. 

INDO-CHINA 

Lead ores are found in Annam and Tonkin, but usually 
in deposits noted more especially for their zinc content. 

At the Bong-Mieu mines, about 100 km. south-west of 
Tourane, galena and pyritic concentrates are obtained from 
the arsenopyrite lodes during the extraction of gold. The 
Quan-Son deposit, in the province of Thanh-Hoa, consists 
of blende and galena in Triassic limestone near the contact 
with schists. Work on a fairly large scale has been done, 
and some hundreds of tons of ore have been extracted. Argenti- 
ferous lead and blende were at one time worked by the Chinese 
at Moa-Ha, in the province of Vinh, but the deposits are now 
abandoned owing to difficulties with water. 

In Tonkin, the Trang-Da mine on the left bank of the 
River Claire, formerly worked by the Chinese for galena, has 
been operated since 1906 by the Socie'te' Civile de la Mine de 
Trang-Da. This company has mined about 90,000 tons of 



102 



SOURCES OF SUPPLY OF LEAD ORES 



calamine, but at the present time the mine is producing galena 
mixed with various percentages of pyrite and blende. The 
country rocks consist of limestones and schists. 

At the Lang-Hit mines, 17 km. north of Thai-Nguyon, 
galena in small quantities occurs with blende and calamine. 
The ore occurs in parallel fractures in similar country to that 
at Trang-Da, and maximum deposition is found where these 
fractures are intersected by secondary ones. 

Galena, associated with brown haematite, calamine and 
cerussite in a baritic and flinty gangue, occurs at Pia-Ka in 
much fractured limestones and schists. 



JAPAN 

This country has a number of lead-ore deposits, the most 
important being that which is worked at Kamioka, in the 
province of Hida. The ore-body is a contact deposit occurring 
at the margin of a quartz porphyry intrusive into gneiss, and 
carries both galena and blende. The lead concentrate pro- 
duced is smelted locally. 

At Akita, in the island of Sado, on the west coast, occur a 
series of veins connected with Tertiary volcanic rocks. In 
certain of these argentiferous galena, associated with sulphides 
of silver, zinc and iron, occurs and is mined. Ores of copper 
and manganese also are produced in this region. Lead ore is 
mined in similar deposits near Tokyo. 

Some recent imports of lead into Japan are given in 
Table XXIX. 

Table XXIX 

Imports of Lead into Japan 
In long tons (2,240 Ib.) 





1910. 


1911. 


XQia. 


1913. 


1914. 


1915- 


1916. 


1917. 


1918.* 


Ingots and slabs 
Plates and sheet 
Tea lead . 


11,528 

356 

809 


14,435 
261 

835 


7,867 
410 
760 


H. 6 43 
152 
544 


15,257 
178 

453 


14.30 
45 
1,103 


20,480 
899 


15.519 
536 


29,783 
271 


Totals 


12,693 


I5.53I 


19,037 


15.339 


15,888 


15.448 


21,379 


16.055 


30,054 



* Ten months. 



ALGERIA TUNIS MEXICO 103 

AFRICA 

The bulk of the lead ore at present produced in Africa 
comes from the countries bordering the Mediterranean. The 
ore is largely exported as such, only small quantities being 
smelted locally. 

ALGERIA 

Lead ores are mined here in a number of localities, and im- 
portant quantities have been exported to France. Many of 
the deposits are metasomatic replacements of the Tertiary 
Nummulitic Limestone, which is well developed in the region 
of the Atlas Mountains. The ores of lead are associated with 
those of zinc, the latter often being predominant. One of the 
principal producing mines, so far as lead is concerned, is that 
of Oued Moziz, in the Department of Oran. 

TUNIS 

The deposits of this country, like those of Algeria, are 
principally metasomatic replacements in Nummulitic Lime- 
stone, along the contacts of schists and quartzites. The 
galena is seldom argentiferous and is generally associated with 
considerable quantities of blende. Cerussite and calamine are 
of frequent occurrence. 

Before the war several thousand tons of lead ore were being 
annually exported from Tunis to France, the United Kingdom 
and Austria- Hungary. France also received small quantities 
of lead. 

NORTH AMERICA 

The output of lead ore in America is very considerable, since 
the United States and Mexico together produce nearly half the 
world's total annual output. 

MEXICO 

Large quantities of lead ore are mined in this country, and 
for many years it has maintained a foremost place among the 
world's producers. Many of the rich silver mines for which 
this region is noted have become, with the deepening of the 
workings, important sources of lead. This metal is very 
8 



104 SOURCES OF SUPPLY OF LEAD ORES 

generally distributed in the numerous veins which occur in 
association with Tertiary volcanic rocks throughout the 
mountainous region of the Sierra Madre. Generally speaking, 
these veins carry rich silver ores in the upper zones, and 
galena and blende, in association with sulphides of copper and 
iron, in the deeper zones. 

Deposits of lead ore occurring as metasomatic replacements 
in limestone are found in several parts of Mexico. One of 
the most celebrated is that of Sierra Mojada, where large ore- 
bodies occur at or near the contact of the limestone with a 
breccia. The galena is exceptionally rich in silver. In the 
State of San Luis Potosi the ores consist principally of cerus- 
site and pyromorphite, in association with native silver and 
silver chloride. 

Jamesonite is mined near Zimapan [59]. 

The disturbed conditions during the Mexican revolutions 
caused a general stoppage of mining, and the output of lead 
ore, among others, seriously declined. During the last few 
years, however, operations have been largely resumed, and in 
1917 considerable amounts of high-grade lead ore were pro- 
duced from the mines of Santa Barbara, Cuatro Cienegas and 
Santa Eulalia, while the Angangueo Mines in Michoacan were 
reopened. 

Recent Mexican productions of lead in metric tons were : 
for 1916, 19,970 ; for 1917, 64,125 ; for 1918, 98,837 ; and 
for 1919 (9 months), 50,534. 

UNITED STATES 

This country is the world's largest producer of lead ore, and 
contains some of the most remarkable deposits known. A 
valuable account of the occurrences together with a history of 
the mining and treatment of the ores was given by Ingalls in 
1908 [60], whose work has furnished much of the information 
given here. 

Following Ingalls we may conveniently group the lead-pro- 
ducing districts of the United States into three regions as 
follow : the Atlantic Coast, the Mississippi Valley, and the 
Rocky Mountains and Pacific Coast. The chief production 
now comes from the Mississippi Valley. 



UNITED STATES 105 

Table XXX, taken from Mineral Resources oj the United 
States for 1917 [6i/p. 888] shows the output of lead-produc- 
ing ores from the several States during that year, and their 
recoverable lead content. 

It will be seen that the recoverable lead content of all the 
ore was 628,321 short tons. To this has to be added 22,628 
short tons of lead obtained as a by-product from other kinds 
of ore. The percentages of total lead derivable from the 
several kinds of ore were : 

Lead ores . . . . . .69-1 

Lead-zinc ores . . . . .26-8 

Zinc ores ...... 0-6 

All other ores . . . 3-5 

ico-o 

The Atlantic Coast 

The mines of this region were never very large producers, 
though they played a not inconsiderable part in the early 
history of lead mining in the United States, but at the present 
time they are mostly abandoned and of little importance. The 
chief are those near Rossie, St. Lawrence Co., N.Y. ; at Guy- 
mard, Ellenville, and Wurtsboro, near Port Jervis, N.Y. ; and 
in Wythe Co., Virginia. The latter are of more importance 
as a source of zinc than of lead. Deposits of lead ore are found 
also in New England, North Carolina and Tennessee. 

The Mississippi Valley 

This area is characterized by a widespread occurrence of 
lead and zinc ores, these being found in the States of Missouri, 
Arkansas, Oklahoma, Kansas, Illinois, Iowa and Wisconsin, 
though they are not everywhere of sufficient importance to 
warrant exploitation. The largest deposits occur in Missouri. 
The chief mining undertakings are located in three districts 
which may be referred to as : 

(1) South-eastern Missouri. 

(2) South-western Missouri, including neighbouring portions 
of Kansas and Oklahoma (Joplin district). 

(3) Wisconsin-Iowa-Ittinois district (Upper Mississippi 
Valley). 



106 SOURCES OF SUPPLY OF LEAD ORES 



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UNITED STATES 107 

The first two constitute the Ozark region of some authors 
[62] [63]. In 1917 this area produced 381,815 short tons of 
concentrate. 

The deposits are contained in gently-dipping Palaeozoic lime- 
stones, ranging in age from Cambrian to Lower Carboniferous 
(Mississippiari), and are found usually within a few hundred 
feet of the surface. The ores occur in dolomitic and cherty 
limestones, as disseminations ; in more or less horizontal 
sheet- like bodies along bedding planes and zones of brecciation ; 
and in vertical or highly- inclined deposits filling joints, faults, 
and crevices widened by solution (gash veins). The ore-bodies 
often extend in comparatively narrow belts for long distances, 
forming the so-called runs. Such runs are controlled by 
structural features in the containing rocks. Both actual 
replacement (metasomatism) and cavity-filling have contri- 
buted to the formation of the ore-bodies. 

The deposits generally carry both galena and blende, the 
latter more particularly in the deeper zones, so that many 
mines formerly yielding lead ore are now producing mainly 
zinc ore. Pyrite and marcasite are common associates, chal- 
copyrite is less frequent. Oxidized ores are found near the 
surface. In places the galena carries a little silver, but on the 
whole the deposits are classed as non- argentiferous, and the 
lead produced is marketed as soft lead. 

The ores are generally believed to have been formed by the 
action of atmospheric waters circulating at shallow depths, 
though some regard them as originating from the action of 
ascending thermal solutions. The mineral association, how- 
ever, does not favour this theory. There is an extensive 
literature dealing with this question. 

South-eastern Missouri [62/p. 104] [64] [65]. The deposits 
in this region were the scene of the earliest lead mining in 
the United States, having been discovered and worked in 
the early part of the eighteenth century. In recent years the 
output has been very large, and at the present time the dis- 
trict produces about one- third of the total lead of the United 
States. Zinc ore is practically absent, so that this area is 
essentially a lead producer. 

The deposits are contained in more or less horizontal Cam- 



io8 SOURCES OF SUPPLY OF LEAD ORES 

brian strata, consisting of dolomites and shales resting upon 
the basal La Motte sandstone. The ore-bodies occur at two 
horizons, the chief being the Bonneterre dolomite, immediately 
overlying the sandstone, while the second, less important, one 
is the Potosi dolomite at the top of the Cambrian sequence. 

In the upper formation, which was naturally the earliest 
worked, the ore occurs chiefly as veins and pipes, along joints 
and bedding planes widened by solution, and in the residual 
deposits covering the surface. . Its distribution is very irregular. 
In the Bonneterre, on the other hand, the galena is mainly 
disseminated as a metasomatic replacement through the 
dolomite, though also occurring to some extent in the upper 
part of the formation in the form of veins, sheets and irregular 
masses filling joints, bedding planes, and other openings. The 
disseminated ore-bodies tend to follow certain directions and 
often reach large dimensions, the mine workings in some cases 
being very big. 

The upper deposits were largely exhausted before the dis- 
covery of the disseminated ore in 1864, but are still mined to 
some extent at Potosi, Palmer and Valle. It is the dis- 
seminated deposits, however, which have supplied by far the 
greater part of the lead mined for many years past, and have 
placed this district in the forefront of the lead-producing 
regions of the world. 

The galena is associated with a little pyrite and sometimes 
chalcopyrite, but zinc ore is practically absent. In places a 
nickel-cobalt sulphide, linnaeite, occurs, and is recovered in a 
pyritic concentrate, locally known as "sulphide," which is 
separated from the galena. Calcite is the usual gangue mineral, 
but in the Potosi barytes is found. 

The crude ore produced in 1917 yielded 5-03 per cent, of 
concentrate, and had an average recoverable lead content of 
only 3-5 per cent., being the lowest grade of lead ore worked in 
the United States. Owing, however, to the enormous tonnage 
mined, nearly 6,000,000 tons, the quantity of lead produced 
exceeded that of any other state. 

South-western Missouri (Joplin district) [62/p. 115] [66]. 
This district lies around the city of Joplin, after which place it 
is usually named. It embraces an area of about 1,000 square 



UNITED STATES 109 

miles, situated principally in Missouri, but including also 
neighbouring portions of Kansas and Oklahoma. The prin- 
cipal mining camps are at Aurora, Granby, Webb City, Alba, 
Neck, Joplin, Galena, Badger, Quapaw and Miami. The 
deposits were discovered in 1850 and were for many years 
mined only for lead ore ; zinc ore was produced in 1870, since 
which time it has become increasingly important, and at the 
present day is entirely predominant. This district has yielded 
considerably over 1,000,000 tons of lead concentrate and 
5,000,000 tons of zinc concentrate. The crude ores are now 
said to average about 5-0 per cent, of concentrate, but were 
formerly much richer. 

The deposits are mineralizations of brecciated chert, and 
occur chiefly in the Boone formation of Lower Carboniferous 
(Mississippian) age, consisting of from 250 to 350 ft. of lime- 
stone and chert. They are found also in the overlying Chester 
and Cherokee formations, and in the underlying Kinderhook. 
Near the surface the ore-bodies occur as elongated lenses or 
irregular masses in or around old sink holes and caverns filled 
with clay and brecciated chert (broken ground), while below, 
at depths of from 150 to 300 ft., they are found as more or 
less horizontal sheets or blanket veins (sheet ground) in a 
brecciated cherty member of the Boone formation. This 
ground is from 6 to 15 ft. thick. In the underlying Kinder- 
hook rocks disseminated ore occurs but is practically unworked. 

In the upper deposits galena predominates, and large bodies 
of this ore have been mined. In the sheet ground, which is 
now the chief source of ore, blende is the prevailing mineral, 
and at the present time this area ranks chiefly as a producer 
of zinc. 

Wisconsin-Iowa-Illinois District [67] [68]. The ores of this 
region occur principally in the Galena dolomite and in the 
upper part of the underlying Platteville or Trenton limestone 
of Ordovician age. The former, which is from 250 to 275 ft. 
thick, is the main ore-bearing horizon. The beds are gently 
inclined and mining operations extend down to a depth of 
about 200 -ft. from the surface. This district is noted for the 
occurrence of ore in flats and pitches, bodies formed of a 
central flat sheet from the margins of which ore extends down- 



no SOURCES OF SUPPLY OF LEAD ORES 

wards in an inclined or step-like manner. It is found also in 
gash veins occupying vertical joints or crevices enlarged by 
solution, as flat sheets along bedding planes, and disseminated 
through the limestone as a metasomatic replacement. The 
first ore obtained from this district occurred in the superficial 
residual clays, where it was discovered towards the close of 
the seventeenth century. 

The upper zones of the ore-bearing beds are characterized 
by galena and zinc carbonate, while below blende pre- 
dominates, associated with some galena and marcasite. Cal- 
cite is the common gangue mineral, but dolomite and barytes 
are found also. Lead ore occurs most abundantly in the 
southern portion of the district, in the vicinity of Galena, 
Illinois ; and Dubuque, Iowa, while zinc ore is more important 
in the north-east, where the lower beds of the ore-bearing 
horizon are chiefly exposed. At the present time most of the 
lead produced comes from the mines situated around Mineral 
Point and Platteville, in Wisconsin. 

Other places in the Mississippi Valley where lead ores are 
mined are Central Missouri and Northern Arkansas, but these 
deposits are small as compared with those already considered 
and have not been exploited to any important extent. 

The Rocky Mountains and Pacific Slope 

Argentiferous lead ores are widely distributed in this region, 
and have furnished material for a thriving smelting and refin- 
ing industry. At the present time, however, the mining is of 
less importance than formerly owing to the exhaustion or 
impoverishment of many of the deposits, and several of the 
smelters have closed down or now rely largely upon imported 
ores. 

This region is famous for a wonderful development of lime- 
stone replacement deposits, some of which have been truly 
remarkable and rank among the great ore-deposits of the 
world. An outstanding feature of these deposits has been the 
extensive development of oxidized ores, large quantities of 
which have been raised. The richly argentiferous character 
of the galena is notable, and considerable quantities of gold 
slao have been obtained from some of the deposits. 



UNITED STATES ill 

Arizona. Silver- lead deposits have been worked in this 
state since early times in the history of American mining, 
though the ores were raised chiefly for then- silver content. 
Operations were conducted chiefly at Mowry, Eureka, Castle 
Dome, and Tombstone, in Southern Arizona, but practically 
ceased in the eighties. In recent years the district has re- 
ceived renewed attention. 

The Hualpai mining district in North-western Arizona con- 
tains veins in Pre- Cambrian schists and gneisses, associated 
with granite and granite-porphyry. The upper parts of the 
deposits yielded rich silver ores, but primary sulphides were 
encountered in depth. This ore, which carries pyrite, galena, 
blende and chalcopyrite, contains 8 per cent, lead and 5-10 
per cent, zinc, together with 15 oz. of silver to the ton, and 
some gold. 

California. The only really important lead- producing dis- 
trict in this state has been Cerro Gordo, in Inyo County, 
which at one time had a considerable output, reaching its 
maximum in 1874, after which it declined and ultimately ceased 
owing to impoverishment of the deposits and troubles due to 
litigation. After a long period of idleness the district was 
reopened in 1906. The ores are contained in steeply- dipping 
veins traversing slate and limestone intersected by various 
intrusive rocks. The veins are very varied in width, rapidly 
swelling and pinching, a character which makes their mining 
very uncertain and speculative. Large quantities of anglesite 
and cerussite were obtained from the upper parts of the veins, 
giving place to galena in depth. The ore ran high in silver, 
some of it containing as much as 140 oz. to the ton. 

Lead ore has been obtained also from the Darwia district, 
where there are large deposits yielding argentiferous carbonate 
and sulphide. In 1917 the state yielded 65,596 tons of con- 
centrate. 

Colorado. For many years this state was the leading pro- 
ducer of lead in the United States, though the output has now 
considerably decreased. The chief producing district has been 
Leadville, other important ones being Aspen, Monarch, Red- 
cliff, Ten Mile, Silver Cliff, and the San Juan region. Colorado 
produced in 1917, 440,909 short tons of lead concentrate. 



112 SOURCES OF SUPPLY OF LEAD ORES 

The Leadville district [i] [69], discovered in 1875, has 
yielded an enormous production of lead and silver, together 
with zinc, copper, gold, and manganiferous iron ore. The 
output reached a maximum in 1883, declined rapidly in the 
nineties, but was resuscitated in 1900. In latter years impor- 
tant bodies of oxidized zinc ores, calamine and hemimorphite, 
have been discovered [70]. 

The deposits consist chiefly of replacements in limestone at 
the contact with intrusive sheets of porphyry, but ore has 
been found also in fault fissures traversing the limestones and 
extending into the underlying Cambrian quartzite. The main 
ore-bearing horizon is in the Blue Limestone, of Lower Car- 
boniferous age, along its contact with the overlying White 
Porphyry. There is a second, lower, contact with a smaller, 
more irregular, Gray Porphyry both in the Blue Limestone 
and in an underlying White Limestone of Silurian age, but this 
is less important. Some of the ore-bodies reached enormous 
dimensions. The rocks have been much folded and displaced 
by faults of considerable throw so that the structure is some- 
what complex. 

Emmons came to the conclusion that the ores were formed 
by aqueous solutions derived from above, most probably from 
the neighbouring porphyries, but the more recent observations 
of others favour the theory of ascending solutions from an 
underlying granite. 

At first the mines yielded large quantities of oxidized lead 
ores, cerussite and anglesite, with some pyromorphite, and 
rich silver minerals, associated with oxides of iron and man- 
ganese, but these gave place at lower levels to mixed sulphide 
ore, consisting of blende and pyrite with galena and chalcopy- 
rite. Considerable quantities of gold have been produced -also. 
At the present time lead ore proper constitutes only about 5 
per cent, of the output of the district ; considerable quantities 
of oxidized zinc ore are raised, but the preponderating pro- 
duct is a mixed sulphide ore consisting chiefly of blende and 
pyrite, with some galena and chalcopyrite. 

The Leadville deposits form part of a belt which extends in 
a north-easterly direction for eighty miles into Boulder County, 
and similar ore-bodies occur in the Ten Mile, Redcliff, and 



UNITED STATES 113 

other districts. In the northern end of the belt gold veins, 
telluride veins, and tungsten veins are found, probably repre- 
senting a higher zone of deposition than that of the lead-zinc 
deposits occurring farther south. 

The Aspen district, in Pitkin County [71] [72], ranks, after 
Leadville, as the second largest producer of lead ore in Colorado. 
It came into prominence in 1884, with the discovery of veins 
carrying rich silver sulphides, and was at first essentially a 
silver camp, but the mining declined in 1893 with a drop in 
the price of that metal. Subsequently lead ore became 
important, while in recent years the production of blende 
has increased. The deposits chiefly follow faults in the Car- 
boniferous limestone, which the ore has replaced. In addi- 
tion to the veins carrying galena and blende there are others 
containing barytes. 

In 1917 the production of lead concentrate was 74,389 tons. 
The ore mined carried 9-10 per cent, lead and 3 oz. of silver 
to the ton, present mainly as polybasite. 

The deposits of the Monarch and Chalk Creek districts, in 
Chaffee County, formerly yielded large quantities of carbonate 
ore, but at present the product is mainly a mixed ore consist- 
ing of blende, galena, pyrite and chalcopyrite. The lead 
concentrate produced in 1914 amounted to about 1,000 tons. 

In the Silver Cliff district, in Custer County [73], deposits 
containing galena, blende, tetrahedrite, argentite, etc., in a 
gangue of calcite, barytes and quartz, occur at the contact 
between rhyolitic tuff and Pre-Cambrian gneiss. In the 
Geyser Mine the ore-body has been worked to a depth of over 
2,000 ft. 

The San Juan region in South-west Colorado, though per- 
haps best known for its yield of gold and silver, is also the 
site of important lead and zinc deposits. The chief mining is 
located in the districts of Telluride, Ouray, Silverton, Lake 
City, Rico, Needle Mountains, La Plata and Creede. There 
is an extensive literature relating to these deposits, and the 
region includes many well-known mines, such as the Enter- 
prise [74], the Camp Bird [75], noted more especially for its 
gold values though some lead is recovered, and others. 

The region is composed largely of a thick mass of Tertiary 



ii4 SOURCES OF SUPPLY OF LEAD ORES 

volcanic rocks overlying Palaeozoic and Mesozoic sediments, 
into which are intruded masses of monzonite. The ores are 
contained in a series of fissure veins, many of which have been 
traced continuously for several miles. In addition there are 
replacement deposits in the sedimentary formations and 
contact deposits at the margins of the intrusive rocks. Some of 
the ore-bodies have been mined to depths of several thousand 
feet. The genesis of the deposits is attributed to solutions 
ascending from deep-seated magmatic sources. 

The chief values are in gold and silver, but in some places 
important deposits of lead and zinc have been mined, the ores 
of galena and blende being usually associated with more or 
less copper in the form of tetrahedrite. The gangue minerals 
comprise quartz, calcite, rhodochrosite, rhodonite, barytes and 
fluorspar. The veins are often beautifully banded, and vary 
in width from a few inches up to many feet. 

The main lead occurrences are in the Silverton district, 
with an annual lead production of about 5,000 tons ; Rico 
district, where the ores occur chiefly in bedded veins (blankets), 
following lines of stratification ; Lake City district, which has 
yielded upwards of 40,000 tons of lead from veins carrying 
galena, pyrite, blende and tetrahedrite, the last being rich in 
silver ; and the Creede district, where veins intersecting rhyo- 
lite carry considerable quantities of galena and blende in a 
gangue of quartz, barytes and fluorspar. 

Idaho. This state produced in 1917, 583,439 short tons of 
lead concentrate, principally from the Cceur d'Alene district. 
Lead ore was discovered here in 1884, in veins traversing a 
thick series of folded and faulted Pre-Cambrian quartzites 
and slates, with some limestone, invaded by large monzonitic 
intrusions. The ores, which occur both as fissure fillings and 
as metasomatic replacements of the bordering country rocks, 
consist of argentiferous galena, accompanied by blende and 
pyrite, associated with large quantities of siderite and sub- 
ordinate quartz. Although the galena may sometimes occur 
massive the ore is usually an aggregate of galena and siderite. 
The ore-bodies are large and the veins remarkably persistent, 
the Bunker Hill vein, for example, being traceable for 7,000 
ft. Mining has_been carried to depths of over 2,500 ft. 



UNITED STATES 115 

The crude ore, which contains on an average 8 per cent. 

lead and 5 oz. of silver to the ton, is classified as lead ore and 

as lead-zinc ore. The lead concentrate yields 50 per cent. 

lead and 30 oz. of silver to the ton. 

In 1917 the Cceur d'Alene district produced 186,004 tons ol 
lead, 38,862 tons of zinc, 1,438 tons of copper, 11,241,126 oz. 
of silver, and $88,683 worth of gold, having a total value 
f 850,054,297. The principal mines are the Bunker Hill 
and Sullivan, the Standard-Mammoth, the Morning, and the 
Hercules. 

In the Wood River district the ores occur in thin veins 
traversing Carboniferous calcareous shale in the neighbour- 
hood of a diorite intrusion. The ore shoots are very irregular 
and their mining uncertain. The ore consists of galena, 
often massive, blende, and argentiferous tetrahedrite, with a 
little pyrite and chalcopyrite, in a gangue composed chiefly 
of siderite or a closely allied carbonate. A little gold is usually 
present. The crude ore is concentrated to a product yielding 
33 per cent, lead and 50 oz. of silver to the ton. The chief 
mines are the Minnie Moore, the Croesus, the Bullion, the Red 
Elephant, and the Red Cloud. 

At South Mountain argentiferous galena and blende occur 
in a deposit at the contact of limestone and diorite, furnishing 
a good example of this class of ore-body. 

Montana. In the contact zone of the Helena batholith there 
are several lead-bearing veins, one of which, the well-known 
Alta vein, is said to have yielded over $32,000,000 worth of 
lead and silver and to be one of the greatest silver-lead deposits 
in the world. 

The ore raised in this district at present is a mixture of 
argentiferous galena and blende with some copper ore. In 
1917 the lead content of the ore mined was, in lead ores, 
2,778 tons ; in lead-zinc ores, 5,728 tons ; in zinc ores, 1,770 
tons ; and in all other ores, 700 tons, making a total of 10,976 
short tons [8i/p. 888]. 

At Elkhorn there are large replacement deposits in lime- 
stone from which considerable quantities of oxidized and 
sulphide ores have been obtained. 
Nevada. By far the most important lead-producing dis- 



n6 SOURCES OF SUPPLY OF LEAD ORES 

trict in this state has been Eureka, though at present the 
output is insignificant, amounting only to about 150 tons of 
concentrate annually. The mines were reopened in 1906 
after a period of abandonment. 

The deposits consist of large replacement bodies in lime- 
stone along its faulted contact with quartzite. Considerable 
quantities of oxidized ores, including arsenates, phosphates 
and molybdates, were raised at one time, but in depth, the 
ore-body became sulphidic. The galena is richly argentiferous 
and some gold is present also. 

At the present time the bulk of the lead output of Nevada 
comes from the Pioche, the Yellow Pine, and the Cherry Creek 
districts. 

New Mexico. Like many other of the Western States, New 
Mexico shows a decreasing output of lead ore, and the mining 
industry is far less important than formerly. The best-known 
undertakings are the Magdalena Mines, where large deposits 
occur in Palaeozoic limestone at the contact of a granite- 
porphyry. The ore-bodies, which are lenticular, follow the 
bedding planes of the limestone, and are found up to 40 ft. 
in thickness. There are five ore-bearing horizons, only one of 
which, however, is important. In the oxidized zone the yield 
was mainly lead and silver, but in depth large bodies of blende 
were encountered. 

At present the leading production of lead from this state 
comes from the Grant and the Cook districts, where the ore 
occurs in fissure veins traversing granite. 

Utah. This state produced in 1917, 696,421 short tons of 
lead concentrate. Salt Lake City is the seat of an important 
lead-smelting industry. 

The deposits are situated in the Bingham, Park City, Tintic, 
and Frisco districts, the first mentioned being now the leading 
producer. 

In the Bingham district the deposits occur as replacements 
in limestone at its junction with quartzite or porphyry. The 
oxidized zone, carrying carbonates and sulphates, extends to 
considerable depths. 

In the Park City district [76] the ores occur both as replace- 
ment bodies along bedding planes in limestone and in fissures 



UNITED STATES 117 

traversing a series of folded and faulted limestones, quartzites, 
and shales of Carboniferous and later ages, in the neighbour- 
hood of large dioritic intrusions. The fissure deposits, which 
carry galena, blende, tetrahedrite and chalcopyrite, in a 
gangue of quartz and jasperoid, with fluorspar, calcite and 
rhodonite, have been worked to considerable depths, but there 
contain more zinc and copper. The richest lead ore-bodies 
have been the bedded deposits. Since 1877 this district has 
produced well over a million ounces of silver and about half 
a million tons of lead. In recent years the output of zinc 
and copper has increased. The concentrate produced at 
present contains 12 per cent, lead, 6-8 per cent, zinc, 9 oz 
of silver to the ton, and some gold and copper. 

In the Tintic district [77], south of Salt Lake City, the ore- 
bodies consist of large replacement deposits and fissure fillings 
along bedding planes, fissures and joints in limestone, in the 
vicinity of a monzonite intrusion. The ore consists of galena, 
blende, and, locally, enargite, with quartz, jasperoid, car- 
bonates and barytes. The galena is rich in silver, while gold 
accompanies the occurrence of enargite. 

In the Frisco district veins and replacement deposits occur 
in Palaeozoic limestones, shales and quartzites, overlain by 
andesitic lavas and intruded by monzonite. Veins in the 
intrusive carry chiefly copper and zinc. 

The celebrated Horn Silver Mine, in Beaver County, is still 
a producer. The deposit occurs at the junction of limestone 
and andesite, and there is a considerable replacement of the 
former. The oxidized zone extends to a depth of about 600 
ft. and carries large quantities of anglesite. Complex sul- 
phates, like plumbojarosite, are rather abundant. This mineral, 
which is a basic sulphate containing lead and iron, has been 
found elsewhere in Utah [78]. 

The Cactus Mine, which at present raises mainly copper, 
was at one time an important producer of lead and silver. 

Consumption oj Lead in the United States 

The United States, although the largest producer of lead ore 
in the world, imports considerable quantities in order to satisfy 
her large smelting industry. The decline of lead mining in 



Ii8 SOURCES OF SUPPLY OF LEAD ORES 

the Western States, due to the abandonment of many of the 
largest mines towards the close of the last century, had a 
serious effect upon the large smelters which had grown up 
with the mining industry, and many had to close down, or to 
continue operations with the help of imported ores. The 
magnitude of the consumption of lead by the United States 
may be gathered from the following figures for 1917, in short 
tons : 



Recoverable from domestic ores 

Imports from all sources 

In warehouses, January I, 1917 

Total exports . 

Stock in warehouses, December 31, 1917 

Consumption . 



548,450 

78.272 

. 12.369 

639,091 
.98,877 
. 26,909 125,786 

513,305 



Tables XXXI, XXXII and XXXIII give details of some 
recent import and export trade of the United States. 



Table XXXI 

Imports of Dressed Lead Ore into the United States 
ending June ^oth) * 

In short tons (2,000 Ib.) 



(years 





1916. 


1917. 


1918. 


1919. 


From British countries : 
Canada .... 
Australia 
Other British countries . 


15,840 
21,308 
303 


8,777 
2,880 


26,050 
9,517 


11,618 


Totals (British) . 


37.451 


11.657 


35,567 


11,618 


From foreign countries : 
Mexico .... 
Chile .... 
Other foreign countries . 


51,958 
6,982 
3,160 


79,357 
9,"7 
13,813 


72,879 
1,864 

399 


78,424 
919 
7, 6 45 


Totals (foreign) . 


62,100 


102,287 


75,H2 


86,988 


Grand totals 


99,551 


H3.944 


110,709 


98,606 



Foreign Commerce and Navigation, U.S.A. 



UNITED STATES 



119 



Table XXXII 

Imports of Lead into the United States * 
In short tons (2,000 Ib.) 





1915. 


1916. 


1917. 


X9i8.t 


>99-t 


From British countries t 
United Kingdom 
Canada, etc. . 


2 

35 


2 

'35 


54 
172 


2,506 


44 


Totals (British) . 


37 


137 


226 


2,506 


44 


From foreign countries : 
Mexico .... 
Other foreign countries . 


346 

22 


2,400 
79 


4.107 
233 


2,705 
29 


5.052 
ii 


Totals (foreign) 


368 


2.479 


4.340 


2.734 


5.063 


Grand totals 


4<>5 


2,616 


4.566 


5.24 


5,107 



* Commerce and Navigation of United States. 
f Calendar years. 

Table XXXIII 

Exports oj Lead from the United, States * 

Pigs, bars, plates and old 

Short tons (2,000 Ib.) 





1915. 


1916. 


1917. 


1918. 


1919. 


To British countries : 
United Kingdom 
Canada 
Other British countries . 


42.864 
10,258 
679 


22,057 

31.369 
667 


3.064 
55.149 


61,107 
12,562 


49,893 
8.059 


Totals (British) . 


53.801 


54.093 


58,213 


73.669 


57.95* 


To foreign countries . 
France .... 
Russia .... 
Japan .... 
Other foreign countries . 


8.585 
13,886 
4.550 
15.690 


2.367 
14.938 
14.650 

V-57 


510 
20,981 
4.717 
9.543 


2.530 
4.747 
3.950 

12,211 


i,42 
304 
7.029 
8,236 


Totals (foreign) . 


42.711 


49,012 


35.751 


33.438 


16.981 


Grand totals 


96,512 


103,105 


93.964 


107.107 


74.933 



Foreign Commerce and Navigation of the United States, and Monthly 
Summary of Foreign Commerce of the United States. (The figures include lead 
produced from foreign ore ; years ending June 3oth.) 

9 



120 SOURCES OF SUPPLY OF LEAD ORES 

SOUTH AMERICA 

Several of the South American States are producers of lead 
ore, notably Argentine, Bolivia, Chile, Colombia and Peru, 
and substantial amounts have been exported to the United 
Kingdom and the United States. 

Most of the deposits occur in veins of a similar type to those 
of Mexico, already considered, in which the mining of lead 
has succeeded that of silver. Important mining localities are 
Cerro de Potosi, in Bolivia ; San Jose, in Chile ; Cerro de 
Pasco, in Peru, and many others. 



APPENDIX 
LEAD POISONING 

A great drawback to the use of lead, either in the form of 
metal or its compounds, is its poisonous character. Lead poisoning 
is quite common, for example, among workpeople connected with 
the preparation and use of whitelead. It may be incurred, also, 
through drinking water conveyed by lead pipes, for which reason 
such pipes are sometimes tin-lined. 

The symptoms of the disease are pains in the abdomen, constipa- 
tion, loss of appetite, thirst, nervous prostration, known as " lead 
palsy," epileptic fits and paralysis. A blue line which forms on 
the edges of the gums is due to deposition of lead sulphide. 

A simple treatment for lead poisoning is to give mustard as an 
emetic, followed by Epsom or Glauber salts. Large doses of milk, 
containing white of egg, are beneficial. A good antidote is weak 
sulphuric acid, but this should be administered with caution. 

The smoke from lead smelting furnaces, containing, as it does, 
such substances as lead, arsenic, sulphur trioxide, and sulphur 
dioxide, is highly injurious to animal and vegetable life. 



121 



REFERENCES TO LITERATURE ON LEAD 

The Publications are referred to by Numerals in the Text 

[i] S. F. Emmons, " Geology and Mining Industry of Leadville," 

Monograph U.S. Geol. Survey, No. 12 (1886). 
[2] W. R. Ingalls, " The Distribution and Production of Lead," 

Mineral Industry for 1893, vol. ii, p. 381. 
[3] J. E. Spurr, "Who Owns the Earth?" Eng. Min. Journ., 

Feb. 7, 1920. 

[4] H. O. Hofman, The Metallurgy of Lead, New York, 1918. 
[5] Edward Thorpe, Dictionary of Applied Chemistry, London, 

1912. 

[6] C. D. Holley, The Lead and Zinc Pigments, New York, 1909. 
[7] Arthur H. Church, The Chemistry of Paints and Painting, 

4th ed., London, 1915. 

[8] Report of the Controller of the Department for the Develop- 
ment of Mineral Resources in the United Kingdom. Pub- 
lished by the Ministry of Munitions of War, London, 1918. 
[9] Mines and Quarries, General Report by Chief- Inspector of 

Mines, pt. iii, issued annually by the Home Office. 
[10] J. H. Collins, " Observations on the West of England Mining 
Region," Trans. Roy. Geol. Soc. Cornwall, vol. xiv (1912). 
[n] J. H. Collins, " Lead-bearing Lodes of the West," Trans. Roy. 

Geol. Soc. Cornwall, vol. xii, pp. 690-7. 
[12] Clement Le Neve Foster, " The Lode at Wheal Mary Ann," 

Trans. Roy. Geol. Soc. Cornwall, vol. ix, pp. 152-7. 
[13] T. Morgans, " Notes on the Lead Industry of the Mendip 

Hills," Trans. Inst. Min. Eng., vol. xx (1902), p. 478. 
[14] L. J. Spencer, " Leadhillite in Ancient Lead Slags from the 

Mendip Hills," Report British Assoc. for 1898, p. 875. 
[15] L. C. Stuckey, " Lead Mining in Derbyshire," Mining Maga- 
zine, vol. xvi (1917), p. 193. 

[16] Cyril E. Parsons, " The Deposit at the Mill Close Lead Mine, 
Darley Dale, Matlock," Trans. Fed. Inst. Min. Eng., vol. xii 
(1896), p. 115- 

123 



124 REFERENCES TO LITERATURE ON LEAD 

[17] C. B. Wedd and G. Cooper Drabble, " The Fluorspar Deposits 

of Derbyshire," Trans. Inst. Min. Eng., vol. xxxv (1908), 

p. 501. 
[18] T. Sopwith, " On the Lead-mining Districts of the North of 

England," Trans. North of England Inst. Min. Eng., vol. xiii 

(1864), p. 187. 
[19] Henry Louis, " Lead Mines in Weardale, Co. Durham," 

Mining Magazine, vol. xvi (1917), p. 15. 
[20] William Wallace, The Laws which Regulate the Deposition of 

Lead-ore in Veins ; illustrated, by an examination of the 

Geological Structure of the Mining District of Alston Moor, 

London, 1861. 
[21] W. Nail, "The Alston Mines," Trans. Inst. Min. Eng., 

vol. xxiv (1903), p. 392. 
[22] John Postlethwaite, Mines and Mining in the Lake District, 

3rd ed., Whitehaven, 1913. 
[23] G. H. Morton, " The Geology and Mineral Veins of the Country 

round Shelve, Shropshire," Proc. Liverpool Geol. Soc., 

1869. 
[24] H. E. Roscoe, " On two new Vanadium Minerals," Proc. Roy. 

Soc., vol. xxv (1876), p. 3. 
[25] A. Strahan, " Geology of the Coasts adjoining Rhyl, Abergele, 

and Colwyn " (Explanation of Quarter Sheet 79 N.W.), 

Memoirs Geological Survey, 1885. 
[26] A. Strahan, " Geology of the Neighbourhoods of Flint, Mold, 

and Ruthin " (Explanation of Quarter Sheet 79 S.E.), 

Memoirs Geological Survey, 1890. Supplement in 1898. 
[27] Warrington W. Smyth, " On the Mining District of Cardigan- 
shire and Montgomeryshire," Memoirs Geological Survey, 

vol. ii, pt. 2 (1848), p. 655. 
[28] Clement Le Neve Foster, " Notes on the Van Mine," Trans. 

Roy. Geol. Soc. Cornwall, vol. x (1879), p. 33. 
[29] G. W. Lamplugh, " Economic Geology of the Isle of Man," 

Memoirs Geological Survey, 1903. 
[30] John Mitchell, " The Wanlockhead Lead Mines," Mining 

Magazine, vol. xxi (1919), p. n. 
[31] Special Reports on the Mineral Resources of Great Britain ; 

vol. ii, Barytes and Witherite, 2nd ed. (1916), p. 88, 

Memoirs Geological Survey. 
[32] Warrington W. Smyth, " On the Mines of Wicklow and Wex- 

ford," Records of the School of Mines, vol. i, pt. 3 (1853), 

Memoirs Geological Survey. 



REFERENCES TO LITERATURE ON LEAD 125 

[33] J' Coggin Brown, " Geology and Ore Deposits of the Bawd- 
win Mines," Records of the Geol. Surv. of India, vol. xlviii, 

pt. 3, (1917), pp. 121-78. 
[34] Imperial Institute Report on the Results of the Mineral Survey in 

Southern Nigeria for 1905-6 (1910), pp. 21-5. 
[35] Imperial Institute Report on the Results of the Mineral Survey in 

Southern Nigeria for 1908-9 (1911), pp. 10-12. 
[36] Stanley C. Dunn, " Notes on the Mineral Deposits of the 

Anglo-Egyptian Sudan," Sudan Geological Survey Bulletin, 

No. i, pp. ii, 12 (1911). 
[37] Wm. Versfeld, " The Base Metal Resources of the Union of 

South Africa," Memoir No. i, Department of Mines and 

Industries; also Mining Magazine, Dec. 1919, p. 372. 
[38] O. E. Leroy, Summary Report for 1909, Geological Survey of 

Canada (1910), pp. 131-3. 
[39] J. B. Jaquet, " Geology of the Broken Hill Lode and Barrier 

Ranges Mineral Field, N.S.W," Memoir Geological Survey, 
N.S.W., No. 5 (1894). 

[40] Anon., Mining Magazine, vol. xxi (1919), p. 351. 
[41] L. Hills, Geological Survey Bulletin, No. 19, Department of 

Mines, Tasmania (1915). 
[42] L. Hills, Geological Survey Bulletin, No. 23, Department of 

Mines, Tasmania (1915). 
[43] W- H. Twelvetrees and L. K. Ward, Geological Survey Bulletin, 

No. 8, Department of Mines, Tasmania (1910). 
[44] Ch. Timmerhans, Les gites metalliferes de la region de Moresnel, 

Liege, 1905. 
[45] J- Schmid, " Bilder von den Erzlagerstatten von Przibram," 

Austrian Agricultural Department, Vienna, 1887. 
[46] Herman Miiller, " Die Erzgange des Freiberger Bergrevieres," 

Erlaulerungen zur geol. Special-Karte Saschsens, Leipzig 

(1901), p. 350. 
[47] F. Klockmann, " Beitrage zur Erzlagerstattenkunde des 

Oberharzes," Zeits. fiir prakt. Geol. (1893), pp. 466-71. 
[48] B. Baumgurtel, Oberharzer Gangbilder, Leipzig (1907), p. 23. 
[49] W. Lindgren and J. D. Irving, " The Origin of the Rammels- 

berg Ore Deposit," Economic Geology, vol. vi (1911), pp. 

303-I3- 
[50] R. Beck, Lehre von den Erzlagerstdlten, vol. ii (1909), 

P- 257. 

[51] G. Gurich, " Zur Genesis der oberschlesischen Erzlagerstatten, 
Zeits. fur prakt. Geol., 1903, pp. 202-5. 



126 REFERENCES TO LITERATURE ON LEAD 

[52] A. Sachs, " Die Bildung der schlesischen Erzlagerstatten," 

Centralblatt fur Min., 1904, pp. 40-9. 
[53] J onn Kirsopp, " The Mineral Resources of the Near East," 

The Near East, Aug. 15, 1919. 
[54] " Austrian Mining in Serbia," Engineering and Mining Journal,- 

Nov. 4, 1916, p. 814. 
[55] Norman M. Penzer, " The Minerals of Anatolia," The Mining 

Magazine, vol. xxi (1919), pp. 78, 79. 
[56] G. Maitland Edwards, " Notes on Mines in the Ottoman 

Empire," Trans. Inst. Min. and Met., vol. xxiii (1913-14), 

pp. 197, 198. 
[57] Anon., " The Mineral Resources of Asia Minor," The Mining 

Journal, Oct. 15, 1910, pp. 1202-3. 
[58] A. S. Wheler and S. Y. Li., "The Shiu-Ko-Shan Zinc and 

Lead Mine," Mining Magazine, vol. xvi (1917), p. 91. 
[59] W. Lindgren and W. L. Whitehead, " A Deposit of Jamesonite 

near Zimapan, Mexico," Economic Geology, vol. ix (1914), 

P- 435- 

[60] W. R. Ingalls, Lead and Zinc in the United States, New York, 1908. 

[61] Mineral Resources of the United States for 1917, pt. i, U.S. 
Geological Survey. 

[62] E. R. Buckey, " Lead and Zinc Deposits of the Ozark Region," 
in Types of Ore Deposits, p. 103, San Francisco, 1911. 

[63] H. F. Bain and C. R. Van Hise, " Preliminary Report on the 
Lead and Zinc Deposits of the Ozark Region," Twenty- 
Second Ann. Report, U.S. Geological Survey, pt. 2 (1901). 

[64] E. R. Buckley, " Geology of the Disseminated Lead Deposits," 
Missouri Bureau of Geology and Mines, vol. ix, pts. i and 2 
(1909). . 

[65] A. Winslow, Missouri Geological Survey, vol. vii (1895). 

[66] A. Winslow, Missouri Geological Survey, vol. vi (1894). 

[67] H. F. Bain, " Flats and Pitches of the Wisconsin Lead and 
Zinc District," in Types of Ore Deposits, p. 77, San Fran- 
cisco, 1911. 

[68] H. F. Bain, " Zinc and Lead Deposits of the Upper Mississippi 
Valley," Bulletin U.S. Geol. Survey, No. 294 (1906), pp. 
129-42. 

[69] S. F. Emmons and J. D. Irving, " The Downton District," 
Bulletin U.S. Geol. Survey, No. 320 (1907). 

[70] G. M. Butler, " Some Recent Developments at Leadville," 
Economic Geology, vol. vii (1912), pp. 315-23 ; vol. viii 
). PP- !- 18 - 



REFERENCES TO LITERATURE ON LEAD 127 

[71] J. E. Spurr, Monograph U.S. Geot. Survey, No. 31 (1898). 
[72] J. E. Spurr, " Ore Deposition at Aspen, Colorado," Economic 

Geology, vol. iv (1909), pp. 301-20. 
[73] S. F. Emmons, " The Mines of Custer County, Colorado," 

Seventeenth Ann. Report, U.S. Geol. Survey, pt. 2 (1896), p. 

461. 
[74] T. A. Rickard, " The Enterprise Mine, Rico, Colorado," Trans. 

American Inst. Min. Eng., vol. xx (1897), pp. 906-80. 
[75] C. W. Purington, " The Camp Bird Mine," Trans. American 

Inst. Min. Eng., vol. xxxiii, pp. 499-528. 
[76] J. M. Boutwell, " Geology and Ore Deposits of Park City 

District, Utah," Professional Paper U.S. Geol. Survey, 

No. 77 (1912). 
[77] G. W. Tower, Jnr., and G. O. Smith, " Geology and Mining 

Industry of the Tintic District, Utah," Nineteenth Ann. 

Report, U.S. Geol. Survey, pt. 3 (1898), pp. 603-785. 
[78] B. S. Butler, " Occurrence of Complex and Little Known 

Sulphates and Sulpharsenates on Ore Minerals in Utah," 

Economic Geology, vol. viii (1913), p. 311. 
[79] J. W. Gregory, "The Geological Plan of Some Australian 

Mining Fields," Set. Prog., July, 1906, pp. 15-18. 
[80] E. S. Moore, " Observations on the Geology of the Broken 

Hill Lode, New South Wales," Econ. Geol., voL xi (1916), 

PP- 327-48. 
[81] C. E. Siebenthal, " Lead in 1917," Min. Res. U.S. Geol. 

Surv. 
[82] Report of the Departmental Committee appointed by the Board of 

Trade to investigate and report upon the Non-Ferrous Mining 

Industry, London, 1920. 



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CONTENTS : Introductory Cotton Cotton Production in the Principal Countries and tin 
Chief Commercial Varieties Cotton Growing in British West Africa and Other Parts of tht 
British Empire Klax Hemp Sunn Hemp Ramie Jute and Jute Substitutes -Manila Hemp- 
Banana Kibre Sisal Hemp Mauritius Hemp Bowstring Hemp New Zealand Hemp Brush 
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