What is "grandidierite"

n. (context mineral English) An orthorhombic-dipyramidal bluish green mineral containing aluminum, boron, iron, magnesium, oxygen, and silicon.

Grandidierite is an extremely rare mineral and gem that was first discovered in 1902 in southern Madagascar. The mineral was named in honor of French explorer Alfred Grandidier (1836–1912) who studied the natural history of Madagascar.