Welcome to the NIGERIA mines
The Precambrian basement complex (gneisses, predominant mica schists, quartz schists, quartzites and altered limestones) contains many granitic pegmatites genetically related to the older granites. The minerals found are: feldspars, quartz, tourmaline, garnets, phosphates, and beryl .
1. Sinkankas J. 1981 "Emeralds and Other Beryls" Pensylvania, Chilton Book Co. p. 542-548