Mineral Species: Sapphirine

Chemical Formula: (Mg,Al)8(Al,Si)6O20

Chemical Name: Magnesium Aluminium Silicate

Mineral Class: Inosilicate

Mineral Notes: Sapphirine is a rare silicate whose dark blue colour can closely resemble sapphire, hence the name. It usually forms in metamorphic rocks with abundant aluminium and magnesium but low in silica. It can also occur as a primary magmatic mineral in subsilicic rocks. It forms at least 5 closely related double chain structures. 

Description: A mica-like matrix from which protrude several small crystals of Sapphirine. All show numerous faces, resembling garnet-like form, and have an almost black but nevertheless a distinctly blue colour.

Location: Itrongay, Hormobe Region, Madagascar.