felsites

The red and pink are felsites or fine-grained porphyries; the black and bottle-green are the coarse-grained varieties, easily disintegrating, and forming hollows [Illustration with caption: Fortification on the cliff commanding the right bank of Wady Sharma '.] in the harder granite.

The Land of Midian — Volume 1 Richard Francis Burton 1855

The red and pink are felsites or fine-grained porphyries; the black and bottle-green are the coarse-grained varieties, easily disintegrating, and forming hollows [Illustration with caption:

The Land of Midian 2003