Musgravite

Musgravite
Musgravite from Sri Lanka
General
Category	Oxide minerals
Formula (repeating unit)	(Mg,Fe,Zn)2BeAl6O12
Strunz classification	04.FC.25
Crystal system	Trigonal
Identification
Color	Grey green to green
Fracture	Conchoidal
Mohs scale hardness	8–8.5
Luster	Vitreous
Diaphaneity	Transparent
Specific gravity	3.62–3.68
Optical properties	Uniaxial
Refractive index	nω = 1.739, nε = 1.735
Birefringence	δ = 0.014 to 0.016
References	[1][2]

Musgravite or magnesiotaaffeite-6N’3S is a rare oxide mineral used as a gemstone. Its type locality is the Ernabella Mission, Musgrave Ranges, South Australia, for which it was named following its discovery in 1967.^[2] It is a member of the taaffeite family of minerals,^[2][1] and its chemical formula is Be(Mg, Fe, Zn)₂Al₆O₁₂. Its hardness is 8 to 8.5 on the Mohs scale.^[2] Due to its rarity, the mineral can sell for roughly USD$35,000 per carat.

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