Feldspar var. Sanidine
Itrongay, Betroka District, Anosy Region, Tulear Province, Madagascar
Thumbnail, 2.8 x 2.4 x 1.0 cm

The Itrongay region of Madagascar has produced the finest gem crystals of Sanidine. This exceptional thumbnail is very rare for the fine condition it is in. The crystal is 100% gem, golden, totally transparent, and euhedral. The faces are glassy and textured with small, curvy trenches that look like sub-parallel and tiny worm tracks. This gem Sanidine has a mass of about 12 grams. Specimens of this quality for both gemminess and luster with a good form at the same time are quite uncommon although they have trickled out slowly for years.