Isahara Pegmatite Field, Atsimo-Atsinanana, Madagascar
The district extends from the Isahara village (about 100 km north of Fort Dauphin) north for several tens of kilometers in the direction of the town of Farafangana. In this area numerous pegmatites of the NYF-Miarolitic Class occur. Such pegmatites, locally rich in magnetite, are strongly miarolitic and produce abundant smoky quartz and citrine, colourless to blue topaz (crystals up to 20 kg) colourless, yellow, green and blue to deep blue-beryl, and emerald-green, gemmy tourmaline.Ref: Madagascar, extraLapis English No.1, 2001, p. 64