Hiärneite

Hiärneite is an oxide mineral named after the Swedish geologist Urban Hiärne (1641–1727).^[4] The mineral can be found in rocks that mainly consists of fine grained phlogopite. Hiärneite is the first known mineral that contains both of the chemical elements antimony and zirconium.^[5] The mineral was described in 1997 for its occurrence in a skarn environment in Långban iron–manganese deposit of the Filipstad district, Värmland, Sweden.^[6][3]

Hiärneite
General
Category	Oxide mineral
Formula	(Ca,Mn,Na)2(Zr,Mn3+)5(Sb,Ti,Fe)2O16
IMA symbol	Hiä[1]
Strunz classification	4.DL.10
Crystal system	Tetragonal
Crystal class	Ditetragonal dipyramidal (4/mmm) H-M symbol: (4/m 2/m 2/m)
Space group	I41/acd
Unit cell	a = 15.264 Å, c = 10.089 Å; Z = 8
Identification
Color	Red
Crystal habit	Prismatic, subhedral
Cleavage	None
Mohs scale hardness	7
Diaphaneity	Translucent
Specific gravity	5.44
Optical properties	Uniaxial (+)
Refractive index	nω = 2.120 nε = 2.160
Birefringence	δ = 0.040
References	[2][3]