144 Mechanical and Technical Processes. Materials
qualities too numerous to mention. Sandstone occurs south
of Esna and extends, though not continuously, as far south as
Wadi Haifa. The finest quarries are at Gebel el-Silsila, a few
miles south of Kom Ombo. Granite occurs at Aswan, which
was the chief source of supply, but other quarries known to have
been worked are found near the Wadi el-Hammamat, between
Qena and El-Quseir. Pink, grey, and almost black varieties occur
in close proximity. Alabaster is found in many isolated places, the
chief ancient quarry being that known as Hat-nub, somewhat
south of Tell el-'Amarna. Basalt is found in many places, such
as Khanqa, Abu Za'bal, and the Faiyum, the last being prob-
ably the ancient source of supply. There is an outcrop of
quartzite close to Cairo, known as El-Gebel el-Ahmar or the
Red Mountain. This, however, was not the sole source of supply
in ancient times.
When quarrying limestone, as at Tura or Ma'sara (Fig. 22),
where the best strata are far below the surface of the outcrop,
galleries sometimes extending for several hundred yards in
length were driven into the required stratum, and a ledge was
cut near the roof to enable a man to work with a chisel there,
first to make a narrow vertical trench behind the block to be
extracted, and then to separate it from the stone on either side.
Finally the block was released by driving a series of small
horizontal wedges along its lower edge. In this manner the
blocks left the quarries with a regularity of size almost like
bricks from a brickyard. In a surface quarry the method was
much the same but involved less labour. The hard rocks were
quarried by means of a hard, blunt-pointed tool in conjunction
with metal or wooden wedges, the technique varying with the
period and with the locality.
With certain minor exceptions all the rocks of Egypt had
been worked to a certain extent by middle predynastic times. In
the Old Kingdom and afterwards the stones mentioned above
were used as follows* Limestone was employed for all kinds of