2. The same; with feldspar of dirty-yellowish colour. From the Mandara range, and two similar varieties from the “hills of Dutchie Zangia, Soudan.”
3. Similarly coloured variety, but of smaller grain. From the same places.
4. Large grained variety of the same; the feldspar of a yellowish colour, and in a state of incipient decomposition, with little black mica. Mandara.
5. Variety similar to the preceding; in a state of disintegration: the feldspar decomposing into a reddish earth. From Quarra and Zurmee, Soudan.
6. Granite, both fine and coarse-grained, almost entirely composed of flesh-red feldspar, with indeterminable particles of a black substance, apparently mica. “From the high ridges of Zurma.”
7. The same, small-grained, rather slaty, approaching to gneiss, composed of greyish-white feldspar and quartz, with predominant black small-scaly mica. From Nansarena, Soudan.
8. Portion of a boulder, chiefly composed of fine-grained dirty-grey semicompact feldspar and some quartz; with disseminated particles of magnetic iron ore (a syenitic rock). “Found near Agutefa.”
9. Greenish-grey mica slate, with little admixed quartz and feldspar. “It forms the upper part of the ridges between Quarra and Zurma, Soudan.”
10. Yellowish-grey, soft, and friable mica slate. “From between Duakee and Sackwa, Soudan.”
11. A hard slaty mass, composed of brilliant silvery small scales of mica, penetrated by, or mixed with, brown and yellow hydrous oxide of iron. From the same.