Natural Science in Archaeology

11.2 Building Stone 251
Fig. 11.2 The great rock-cut
temple of Abu Simbel of
Rameses II, south of Aswan
on the west bank of the Nile,
carved out of sandstone rock
cliffs about 1280 BCE
limestones and marbles, but they have relatively high compressive strength. The
often severe directional weaknesses in metamorphic rocks frequently preclude their
use in large-scale structures. Following are summaries of the physical and chemical
characteristics of the major building stones. Readers may want to review these rock
types in Chap. 3.
11.2.1 Granite/Diorite
A typical granite is composed of 65% feldspar, 25% quartz, and 10% hornblende.
The hardness of feldspar and hornblende ranges from 5.0 to 6.5, and the hardness of
quartz is 7.0. Thus, granite is a hard rock. Most granites possess structural features
that are important in the quarrying of dimension stone and material for monuments
or statuary. One of the most important features is parting. Fortunately, one direction
of parting is nearly vertical, and the other direction is nearly horizontal in outcrop.
The ancient Egyptians took advantage of this in quarrying their huge granite
obelisks (Fig. 11.3). Granites normally provide high strength in all directions. The
major drawback of granites is their tendency to spall off in thin layers.
High-quality granites that were widely used for building stone occur throughout
most of the British Isles, in northwestern France, in much of Scandinavia, in
Italy, and in Russia. Iron Age peoples in England used granite blocks picked up
from moors. Perhaps the most famous architectural granitic rock is the syenite outcropping
between Aswan and the first cataract of the Nile River. This rock has
been exploited since the First Dynasty for tombs, temples, and sarcophagi. It was
exported to other parts of the Mediterranean for obelisks and statues. Other wellknown
granites are the gray granite from Aswan that was used for buildings in
Egypt and exported, and the red granite porphyry quarried near the first cataract of
the Nile that was used for sphinxes and statues in Egypt. The Romans shipped this
stone to Italy and other provincial cities throughout the Roman Empire.