Sakenite lenses within a series of biotite-sillimanite-cordierite-garnet gneisses of the Ihosy granulite unit. The sakenite was described by A.Lacroix in 1941.
Ref:
http://christian.nicollet.free.fr/page/Publications/musgravite.html
A.Lacroix (1941): Les gisement de phlogopite de Madagascar et les pyroxenites qui les renferment, Tananarive