Tsaramanga pegmatite (Tongafeno pegmatite), Mahaiza Commune, Betafo District, Vakinankaratra, Madagascar

Pegmatite vein containing gem minerals near Tonga Mountain, 15 km south of the town Betafo. An intensely kaolinized pegmatite cuts granitic-gneisses near their contact with amphibolized gabbroids. Large transparent crystals of blue beryl are found, some of which have yellow or green tints or dark green cores. Spectacular druses of smoky quartz and aquamarine with brilliant faces are found within accumulations of red (pocket) clay. Black tourmaline (schorl)is common. Garnets (almandine-spessartine series), columbite, betafite, metamict zircon, magnetite, molybdenite (as inclusions in quartz), and other minerals are present.

Ref: E.Ya. Kievlenko, Geology of gems, 2003, p. 112

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