Alamosite

Alamosite (Pb₁₂Si₁₂O₃₆) is a colorless silicate mineral named after the place where it was discovered, Álamos, Sonora, Mexico. Its IMA symbol is Aam^[3]) It is a rare secondary mineral occurring in the oxidized zones of lead-rich deposits. For example, the infobox picture shows its association with black leadhillite.^[1]

Alamosite
Transparent crystals of alamosite in the matrix of leadhillite and melanotekite
General
Category	Inosilicates
Formula (repeating unit)	Pb12Si12O36
Strunz classification	9.DO.20
Dana classification	65.7.1.1
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	P2/c
Unit cell	a = 11.209, b = 7.041 c = 12.22 [Å]; β = 113.15°; Z = 12
Identification
Color	Colorless
Cleavage	{010} perfect
Mohs scale hardness	4.5
Luster	Adamantine
Streak	White
Diaphaneity	Transparent to translucent
Specific gravity	6.49
Optical properties	Biaxial (-)
Refractive index	nα = 1.947, nβ = 1.961, nγ = 1.968
Birefringence	δ = 0.021
2V angle	65° (meas.)
References	[1][2]

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