Urusovite

 Urusovite is a rare copper aluminium arsenate mineral with formula: CuAlAsO₅. It is a monoclinic-prismatic light green mineral.

Urusovite
General
Category	Arsenate mineral
Formula (repeating unit)	CuAlAsO5
Strunz classification	8.BB.60
Dana classification	38.05.09.02
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	P21/c
Unit cell	a = 7.314 Å, b = 10.223 Å c = 5.576 Å; β = 99.79°; Z = 4
Identification
Color	Light green
Cleavage	Perfect
Fracture	Brittle
Mohs scale hardness	4
Luster	Vitreous (Glassy)
Streak	White
Diaphaneity	Translucent
Optical properties	Biaxial (-)
Refractive index	nα = 1.672 nβ = 1.718 nγ = 1.722
Birefringence	δ = 0.050
Dispersion	r > v strong
References	[1][2]

Its type locality and only reported occurrence is in the Novaya fumarole, Second scoria cone, North Breach, Great Fissure eruption, Tolbachik volcano, Kamchatka Oblast', Far-Eastern Region, Russia.^[1][2] It was named after Vadim Sergeevich Urusov, crystal chemist of Moscow State University.^[3] It was approved by the International Mineralogical Association in 1998.

This article uses material from the Wikipedia article  Metasyntactic variable, which is released under the  Creative Commons Attribution-ShareAlike 3.0 Unported License.