Natural Grandidierite

Grandidierite was first discovered in 1902 in Madagascar by Alfred Lacroix, a French mineralogist. Lacroix named the mineral in honor of French explorer and naturalist Alfred Grandidier (1836–1912), the first authority on the natural history of Madagascar.

Since its initial discovery, samples of Grandidierite have been found in only a few locations around the world, including Malawi, Namibia and Sri Lanka. But the few gem quality specimens have come mainly from Madagascar.

Gem-quality Grandidierite is extremely rare, and it often appears on the list of the 10 rarest varieties in the world, along with gems like jeremejevite, painite, benitoite and taafeite.

Gemologically, Grandidierite is a magnesium aluminum borosilicate. It has a hardness of 7 to 7.5 on the Mohs scale, similar to garnet; a density of 2.85 to 3.00, in the approximate range of tourmaline; and a refractive index of 1.590-1.623.