Pegmatites of the Amblygonite Subtype, 25 km west of Ikalamavony. The well-exposed dike section is about 200 m long. It consists of a fine-grained, feldspar-rich border zone with muscovite and tourmaline; an intermediate zone with quartz, perthite, albite, beryl
and muscovite; and a core zone of quartz.
South of the locality, another dike is remarkable for an occurence, in the massive, coarse-grained core, of polychrome tourmaline in crystals, some reaching 1 meter in length. This area has become famous for the production of significant crystals of gemmy, yellow to deep-orange beryl
. These often doubly terminated crystals are found without matrix and are more or less corroded on the faces. They can weigh as much as several hundred grams.
Ref: Madagascar, extraLapis English No.1, 2001, p. 61