12. White, massive, and irregularly crystallized fat quartz, stained by oxide of iron. “From a vein in the rocks of Quarra and Zurmee.”
13. The same, out of the granite of the Mandara mountains.
13. a. Yellowish and bluish-white quartz in large grains, as gravel. “From the bed of the river Yaou, seven days on the road to Soudan[126].”
14. Greyish-black close-grained basalt. “From the hills in the Sebha district.”
15. The same; with rarely disseminated grains of decomposing olivine. From the same.
16. The same; vesicular (basaltic amygdaloid), cells empty. Benioleed.
17. The same as the preceding, with disseminated granular particles, and minute acicular crystals of specular iron, which also mostly invest the irregularly shaped cells. “Benioleed; used for grindstones.”
18. The same, of a greyish-brown colour; cells elliptic, and partly filled with carbonate of lime. “Black mountains near Sockna.”
19. Greenish and yellowish grey, fine-grained crumbling sandstone. “Found with the gypsum of the hills to the northward of Om-el-Abeed.”
20. The same, brownish-yellow; “occurring in beds near Om-el-Abeed.”