DESCRIPTIONS OF EGYPT. 
117 
phyry, and granite. The direction of the rocks of 
granite is commonly from north to south, and the 
immense blocks, of which they are composed, some- 
times approach towards regular stratification. The 
granite is red, and marked with dusky spots. The 
surface exposed to the air granulates into a species 
of brownish sand, by the appearance of which, it is 
readily distinguished from the porphyry, into which 
it often graduates. Porphyry, of both the red and 
green species, is found in immense masses, but its 
rocks are not so numerous as those of granite. It 
often graduates into the green unvariegated mar- 
ble, which is hard and brittle, where it meets the 
porphyry. The green marble, according to Bruce, * 
is often intermixed with veins of a yellowish and 
bluish coloured marble, and with jasper of the most 
beautiful kinds. The jasper is green, pellucid, and 
cloudy, but inferior in hardness to rock-crystal. 
This mineral, termed sibergeU and bilw\ by the 
native Bedouins, and zumrud by the Moors, seems 
to be the same which was denominated smaragdus 
by the Greeks and Latins. The verde antico, of 
a dark green colour, marked with irregular white, 
is found in the hills of green marble which lie near- 
est the Nile. The Egyptian pebble, a stone of 
the siliceous order, remarkable for the variety and 
* Bruce's Travels, Vol. I. p. 187. 
