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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,

JC-NRLF

LONDON
JOHN MURRAY, ALBEMARLE STREET, W.

1921

Price 6s. net

IMPERIAL INSTITUTE

MONOGRAPHS ON MINERAL RESOURCES

WITH SPECIAL REFERENCE TO THE

BRITISH EMPIRE

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

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

LONDON

JOHN MURRAY, ALBEMARLE STREET, W.

1921

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.

448396

IMPERIAL INSTITUTE
Advisory Committee on Mineral Resources

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

the Admiralty), (Vice-Ohairman).
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. ELS WORTHY, 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. BANN. 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.

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.?.

October 1920.

vii

CONTENTS
CHAPTER I

PAGE

LEAD ORES : THEIR OCCURRENCE, CHARACTERS

AND USES I

CHAPTER II
SOURCES OF SUPPLY OF LEAD ORES

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 . . . .70

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 deptji. 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 .V 5VK/ 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,
plumbo faro site, though a rare mineral, occurs in certain mines
in Utah in sufficient abundance to be mined [78]. The red
oxide, minium, Pb304, and the yellow oxide, massicot, PbO,
are comparatively rare minerals. The phosphate of lead,
pyromorphite, 3Pb3(PO4)2PbCl2, and the arsenate, mimetite,
3Pb3(AsO4)2PbCl2, (green lead ores), commonly occur with
other secondary lead minerals, although usually only in
small quantity. The closely allied vanadate, vanadinite,
3Pb3(VO4)2PbCl2, may be regarded as an ore of vanadium.
The following are of occasional occurrence: the chromate,
crocoisite, PbCr04, the molybdate, wulfenite, PbMoO4, and
the tungstate, stolzite, PbWO4. In addition to the above there
are numerous other lead- bearing minerals, including tellurides,
selenides, oxychlorides, silicates, etc., which are of mineralogical
interest only ; and of recent formation are the group of oxy-
chlorides (laurionite, 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'l 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.

Jamesonite, 2PbS,Sb2S3 (Pb 50-8, Sb 29-5 per cent.), bou-
langerite, 5PbS,2Sb2S3 (Pb 55-4, Sb 22-8 per cent.), and
bournonite, 3(PbCu2)S.Sb2S3 (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, PbC08 (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, PbS04 (Pb 68-3 per cent.). — This
mineral has a more resinous lustre, and is softer and lighter
than cerussite. Hardness, 27 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.

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
only 3*5 per 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

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

locality.

Raw ore
per cent.
Lead.

Dressed ore.

Per cent.
Lead.

Oz. silver per
ton.

St. Joseph, Missouri

North of England

8-5

70-77

8-00

Bleiberg, Carinthia

0-05

Przibram, Bohemia

37-38

76-50

Freiberg, Saxony
Tarnowitz, Silesia

18-70
75'5

17-88
13-50

Upper Harz, Prussia

25-00

Mechernich, Prussia

56-60

3-4

Kellogg, Idaho .

30-00

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

—

Ag.(«)

Cu.

Pb.

SiOi.

Fe.

Al^Oa.

CaO.

MgO.

Zn.

Ni&C<

Ore

O'I2

0-06

5'7

5-o

4-1

4'9

25-5

I4-2

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

0-05

Medium con-

centrate

i'3

0-12

68-6

1-4

4-6

—

3'i

1-4

0-8

15-5

o-o£

Low-grade con-

centrate

I'O

0-30

65-8

o-5

3'i

o-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

t 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

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.

£ s. d.

1910

12 19 0

1915

22 l6 IO

IQII

13 19 3

1916

30 19 7

IQI2

17 15 10

1917

30 o o

1913

18 6 2

1918

30 2 8

1914

18 13 9

1919

28 3 ii

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 5°°° 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 th.e 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 Cup citation 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 can
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 Betts 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 Hof man'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,

LEAD ORES

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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 ii'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 (Pb20) 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 (Pb3O4), 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

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
:.ts 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

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 hrs.
at Deg. C.

o-5

7-6- 8-2

6-8- 7-1

9-8- 9-9

9-5- 9.7

Antimony .

10-7-10-9

15-1-16-5

230

13-6-13-9

14-0-14-3

16-8-17-3

15-8-16-1

0-5

6-0- 6-4

6-O- 6-4

Tin . ,

6-8- 6-9
8-0- 8-1

6-6- 7-2
7-4- 7-9

270

10-6-10-9

II-3-H-4

230

0-5

9-1- 9-2

8-9- 9-4

Cadmium .

9-5-10-2

II-6-I2-2

9-7-10-1
12-6-12-7

270

16-7-19-8

14-2-14-5

220

o-5

I3.5_!5.5

13-8-13-9

Magnesium

I7-9-I9-6

16-3-16-4

220

22-3-22-6

19-8-20-9

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 2PbCO3,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 CO2 . . . .11-36
Water H2O .... 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 ttie 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 -ire
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 (Pb3O4), 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 an ti- 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- tin ted 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.

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 control
(Commercial).
Per cent.
of total.

Political control
(Geographical).
Per cent,
of total.

United States
British Empire
France
Germany
Spain .
Austria-Hungary
All others

49
I?
13
15

45
13
2

14
II
2
13

100

THEIR OCCURRENCE, CHARACTERS AND USES 35

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

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

— Belgium.

France.

— United Kingdom.

India.

Peru.

— [ • Austria-Hungary.

T ~ —• 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.

LEAD ORES

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THEIR OCCURRENCE, CHARACTERS AND USES 39

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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

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 £51,435,596.

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

Tons lead metal.
England ... . 1,505,819

Wales .
Scotland
Ireland .
Isle of Man

725.055

148,617

36,211

175.143

' 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
'lave had a serious effect upon the mining industry, and diffi-
:ulties connected with shortage of labour and machinery have
:onsiderably curtailed outputs. On the other hand, the
iemand created for home ore supplies and the increase in the
:>rice of the metal have had the effect of directing attention
:o many derelict properties which, under normal conditions,
vere 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, FHntshire 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

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

1915-

1916.

1917.

1918.

1919.

England :

Cheshire

—

Cornwall

Cumberland .

897

839

720-5

706

M05

Derbyshire

3,944

3,232

3,585

2,699

2,930

Durham

4>I23

4,045

3,840

3,369

2,681

Northumber-

land .

648

589

429

909

429

Shropshire

Westmorland

647

735

683

846

640

Yorkshire

42-5

Wales :

Cardigan

1,802

1,163

896

553

391

Carmarthen .

Carnarvon

128

184

141

129

Denbigh

—

Flint

2,721

i,703

824

1,540

1,386

Montgomery .

410

365

Scotland :

Dumfries

3,135

2,333

2,056

»,7J5

1,860

Lanark .

1,943

1,577

i,773

1,952

1,896

Ireland :

Armagh .

—

Sligo .

—

Wicklow

—

Isle of Man

299

203

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

14,095

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] :

SOURCES OF SUPPLY OF LEAD ORES

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

Dressed lead ore

Amount of silver

(in long tons).

content (in oz.).

England :

Cheshire

—

Cornwall

Cumberland .....

706

5.975

Derbyshire ......

2,699

Durham ......

3.369

15,129

Northumberland .....

909

3,944

Shropshire .....

Westmorland .....

846

8,319

Yorkshire . '.

Wales :

Cardigan ......

553

5,134

Carmarthen .....

Carnarvon ......

129

1,650

Denbigh ......

Flint ......

1,54°

10,910

Montgomery .....

Scotland :

Dumfries ......

i,7J5

11,147

Lanark ......

i,952

5,856

Ireland :

Sligo

Wicklow ......

Isle of Man ......

206

9,37°

Totals

14,784

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 [xo/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-copper 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 [1.3]. — 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 (toadstones) 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 aiter 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, srtch 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 [19].

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, Thorn thwaite, 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 linarite, 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 -f 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 . * . r. = 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.)

1911.

1912.

1913-

1914.

I9I5-

1916.

1917.

1918.

1919.

Belgium
Germany
Other countries .

1,309
1,248
283

1,604
492
3i6

2,649
532
377

2,549
945

221

152

210

47s

Totals .

2,840

2,412

3,558

3.715

152

210

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.

I920.J

To British countries : •

India

4,723

4,360

2,641

1,866

2,947

Ceylon

1,265

836

338

217

36i

j4»265

British East Indies

2,162

7°9

Canada

1,019

927

155

382

5,207

South Africa .

1,447

1,010

372

101

145

181

Other British countries

i,337

2,160

352

I78

i, in

—

Totals .

n,953

10,002

3,897

2,365

5,697

9,653

To foreign countries :

France .

4,243

972

1,810

i,37°

Russia ' ,

12,024

10,675

2,398

382

563

Sweden ', <•.

1,618

688

149

1,536

1,960

Denmark v • ,

2,098

562

504

China

227

256

189

2,2IOf

737t

Japan <r>
Java .
South America .

762
1,969

893
2,493
831

74i

727
1,676

5,647
1,609
678

1,381

Other foreign countries

3,907

1,038

310

4,279

12,310

Totals .

28,440

18,408

5,467

2,553

18,655

18,321

Grand totals .

4°, 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.

| 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

he 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 7o°-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

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.

I9I3-I4-

1914-15-

1915-16.

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
161

5,785
1,307
30

2,268
1,110

4,372
2,036

5,096
4,031

554

i,9i5
4,536
1,109

4,121

6,093
133

349

5,897
850

10,031

7,122

3,42i

6,408

9,681

7,56o

io,347

7,096

146

IQO

101

1,165

2,792

222

2,202

10,177

7,312

3,43i

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
Fran$aise 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 :

I^ead.

Zinc.

Copper.

Silver.

Percent.

Per cent.

Per ton.

65-49

o-73

trace

oz 10 dwt.

15 gr.

55-21

6-99

0-56

„ 6 ,

38-87

3-49

trace

„ 8 ,

33-31

I'll

0-088

„ 19 ,

24-65

i-33

0-04

„ 18 ,

0-82

30-40

0-12

7 .

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
t of Johannesburg, and similar deposits are known in

)? N.orthern 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,
in 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-

:i 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.

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 aboul
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 lb.)

1911.

1912.

1913-

1914.

1915.

1916.

1917.

1918.

1919.

British Columbia .
Yukon, etc. .

10,791

16,226

17,072
i7

16,465

20,552

457

17,766
1,062

13.377

1,403

21,594
1,726

19,91;

Totals .

10,791

16,226

17,089

16,487

21,009

18,828

14,780

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

I AUSTRALIA ?t

e-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 sources 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

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

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

40]-
Tasmania. — There are several important lead- zinc deposits

mown 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, siderite 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.

I,ead.

Copper.

Silver.

Gold.

Per cent.

Ounces
per ton.

*ossan ....

—

9'47

—

21-9

0-50

-ead ore ....

28-0

9-35

—

12-7

O-2O

'inc ore ....

40-8

7-0

—

9'7

0-157

x^pper ore

—

4-4

2-0

~—

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-
.and, so far little has been done to develop them commercially,
[n many cases lead is found as a subsidiary metal in gold and
diver deposits.

The Hauraki Peninsula, in North Island, is extensively
mineralized and contains an assemblage of veins connected
vith Tertiary volcanic rocks. Several of these deposits have
Deen worked for gold with highly successful results, as in the
^Vaihi 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
ittention.

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

SOURCES OF SUPPLY OF LEAD ORES

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H 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 galena 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

AUSTRIA

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 oj Dressed Lead Ore into Austria-Hungary *

In metric tons (2,204 !&•)

1910.

1911.

1912.

1913-

From British countries :
Australia . . . u .

4,00 if

—

1,980

6,054

From foreign countries :
Germany . *
Russia
Serbia . .
Tunis
United States

140
146

1,394
674

1 80
497
15

508

298

902

i,9i5
4i

Totals (foreign countries) .

2,354

1,200

1,260

2,001

Grand totals ....

6,355

1,200

3,240

8,055

* Statistik des A uswartigen Handels des Vertragszollgbeites der beiden staaten
der Ostcrr-Ungar Monarchic,
f 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.

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 of Crude Lead into Belgium
In metric tons (2,204 H>.)

From

1910.

1911.

1912.

Australia .

1,505

1,550

2,595

1.896

United Kingdom

2,526

1,464

2,441

Germany

1,344

2,244

^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

33,i62

3L528

Turkey

7,422

3,930

5,126

6,081

United States

1,908

3,672

2,636

2,543

Other countries

i,598

4,809

4,303

6,422

Totals

53,868

83,502

68,039

72,192

BELGIUM

Table XVIII

Exports of Lead from Belgium

(Crude metal, and beaten, rolled or drawn)

In metric tons (2,204 H>.)

1910.

1911.

1912.

1913-

United Kingdom

4.030

3,044

6,143

10,151

France

3o,389

35.306

35.773

47>656

Germany .

15,216

23.3"

18,720

14,284

Netherlands

4.354

4.035

3.I5I

4.584

Russia

7.447

7.351

8,857

6,586

Other countries

4.370

4.915

5.879

3.970

Totals

65,806

77,962

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 in 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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tN O O M
tOvO •"$• N

^- H" t-T

t^.

K^«

iO Ov to CO

•

O M

r^vo t*** t^»

M O^-

vO \O Ov ^

OS
M

!*"• co «o TJ-

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Os O

M- N N C-*

rO o M M

£.

•tj- co

tN CO C^ C^

CM" M"

cf i-T i-T vo"

tN"

"*"

& S

co
to

vO O 00 u->
ITS OsO to

<N" CN"

N M" M" CO"

**"

M Tt-

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M
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CO IO Is* CO

co M"

^t"

CO* w" M" t<"

.3 ' '

a •

I • • • s, *

*••

•

rom British count
United Kingdoi
Australia

Totals (Bri
countries)

rom foreign count,
Belgium
Germany
Spain
Other forei
countries .

T o t a Is (f on
countries)

'rt
o

ft,

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 of Dressed Lead Ore into France *

In metric tons (2,204 Ib.)

1912.

1913-

1914.

1915-

1916.

1917.

From British countries :
Australia .

6,043

—

2,914

—

505

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

9,54i

. 282
6,164
133

2i,i73

9,871
1,363
7»736

IO2

18,615

3,915
824
11,967
706

Totals (foreign coun-
tries) .

36,4H

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 Documents Statistiques . . . sur le 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 Central du Commerce et 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 in 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

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

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 pom Germany *

Rolled (sheet lead, etc.)
In metric tons (2,204 Hx)

1910.

1911.

1912.

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
861
331
405
1,334

561
253
486
280

354
i,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

5,632

* Statistic des Deutschen Reichs Band 260, //.

SOURCES OF SUPPLY OF LEAD ORES

Table XXIII

Exports of Lead from Germany *

Crude (in blocks, pig, etc.)

In metric tons (2,204 lb.)

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

i,94i
8,352
3,154
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

41.369

* Statistik des Deutschen Reichs Band 260, //.

Table XXIV

Imports of Dressed Lead Ore into Germany *
In metric tons (2,204 !*>•)

1910.

1911.

1912.

1913-

From British countries :

Australia

93,48i

I24,8l9

98,252

127,021

British South Africa

307

—

United Kingdom

807

271

Totals (British countries)

93,554

125,725

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

i,32i

3,596

1,279

France ....

3,100

3,008

435

—

South- West Protectorate .

—

1,466

913

Peru ....

1,274

1,748

2,563

2,118

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)

18,597

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 H>.)

1910.

1911.

1912.

1913.

From British countries :
Australia
United Kingdom

8,791
4,184

6,697
6,135

4,103
3,72i

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

13,917
535
20,331
1,882

33,798
3
3,3H
746
11,788
517
35,843
1,699

33,i65

757
1,104
1,266
24,370

1,022
22,928
1,149

13,973
873
2O

835
42,793
680
16,273

i,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, 77.

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 !*>•)

1912.

1913-

1914-

1915.

1916.

1917.

1918.

1919.

Australia .

United Kingdom

717

283

876

189

152

377

119

France

1,816

126

155

406

226

—

Spain

12,661

10,316

7,413

12,227

11,960

21,081

6,567

6,132

United States .

—

155

4.340

763

4,519

269

211

Other countries

433

743

1,221

569

1,077

5,546

5,759

Totals

15,627

11,494

9,820

17,326

14,358

26,279

12,456

12,221

* Ministero 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

g6 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

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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 also 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 6J 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' *. i — V , 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 Ind^lstry 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 Societe 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 oj Lead into Japan

In long tons (2,240 Ib.)

1910.

1911.

1912.

1913.

1914.

1915-

1916.

1917.

1918.*

Ingots and slabs
Plates and sheet
Tea lead .

11,528
356
809

M,435
261

835

7,867
410
760

I4,643
152
544

15,257
178

453

14,300

45
1,103

20,480
899

15,519
536

29,783
271

Totals

12,693

15,531

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

100-0

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-Illinois 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
(Mississippian), 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
ir> 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

lies, situated principally in Missouri, but including also
Leighbouring 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 in

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 their 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 Darwin 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.

H2 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

H4 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 °f
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
of $50,054,297. 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- smelt ing 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 plumbofarostte, 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 of 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

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 .

• 98,877
. 26,909

548,450
78,272
12,369

639,091
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 (years
ending June 30th) *

In short tons (2,000 Ib.)

1916.

1917.

1918.

1919-

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

15,840
21,308
303

8,777
2,880

26,050
9,5i7

11,618

Totals (British) .

37,451

n,657

35,567

11,618

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

5L958
6,982
3,160

79,357
9,H7
13,813

72,879
1,864
399

78,424
919

7,645

Totals (foreign) .

62,100

102,287

75,M2

86,988

Grand totals

99,55i

113,944

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.

I9i8.t

19194

From British countries ;
United Kingdom
Canada, etc. .

2
135

54
172

2,506

Totals (British) .

137

226

2,506

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

346

2,400

4.107
233

2,705
29

5.052
ii

Totals (foreign) .

368

2,479

4.340

2,734

5.063

Grand totals

405

2,616

4,566

5.240

5.107

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

Table XXXIII

Exports of 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

3L369
667

3.064
55,149

61,107
12,562

49.893
8,059

Totals (British) .

53.8oi

54.093

58,213

73.669

57.952

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

8,585
13,886
4.550
15.690

2,367
M.938
14.650
17.057

5io
20,981
4.717
9,543

2,530
M.747
3,950

12,211

1,412
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 June1 3oth.)

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

122

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. 11, 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 Moresnet,

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

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

Erlauterungen zur geol. Special-Karte Saschsens, Leipzig

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

Oberharzes," Zeits. fur 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.

303-13.
[50] R. Beck, Lehre von den Erzlagerstatten, vol. ii (1909),

P- 257-

[51] G. Gurich, " Zur Genesis der oberschlesischen Erzlagerstatten,
Zeits. filr 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] Jonn 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 Jamesbnite

near Zimapan, Mexico," Economic Geology, vol. tx (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- i-18-

REFERENCES TO LITERATURE ON LEAD 127

[71] J. E. Spun, Monograph U.S. Geol. 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.t 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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