Lake Alaotra, Alaotra-Mangoro, Madagascar
Alaotra Lake lies 180 km NE of Antananarivo. Deforestation and the ensuing soil erosion are causing the lake to rapidly fill with sediments. A pegmatite district sits east of the lake and likely extends for tens of kilometers toward the east coast. Most of the pegmatites are medium to small, of the Beryl-Columbite Subtype, and locally produce good gem beryl.Ref: Madagascar, extraLapis English No.1, 2001, p. 46