Translucent blue green Grandidierite crystal. Grandidierite is a rare magnesium aluminum borosilicate first discovered in 1902 in the Anosy Region of Madagascar and often appears on lists of the 10 rarest gems in the world. Crystals are very rare and ususally the best you can hope for are some crystal faces as they ususally grow in narrow seams. Though not terminated, it is crystalized all around and good sized. The quality is excellent with highly translucency great color.