Grandidierite

Precious gem Nesosilicate

7–7.5Hardness (Mohs)

(Mg,Fe)Al₃(BO₄)(SiO₄)OChemistry

1Known origins & mines

One of the ten rarest gemstones on Earth: bluish-green magnesium borosilicate first found in Madagascar in 1902. The 2014 Tranomaro discovery finally yielded clean facetable crystals that fetch tens of thousands of dollars per carat.

Known origins & mines

Tranomaro Grandidierite Deposit · ?

Active mining · Legendary locality

The 2014 Amboasary find finally yielded transparent facetable grandidierite of exceptional bluish green - documented by GIA from one of Eart…

Mineral family: Nesosilicate

Vesuvianite