Sphalerite

Sphalerite
General
CategorySulfide mineral
Chemical formula(Zn,Fe)S
Strunz classification02.CB.05a
Dana classification02.08.02.01
Identification
ColorBrown, yellow, red, green, black.
Crystal habitEuhedral Crystals - Occurs as well-formed crystals showing good external form. Granular - Generally occurs as anhedral to subhedral crystals in matrix. Colloform
Crystal systemIsometric hextetrahedral (Àdàkọ:Overline 3m)
TwinningSimple contact twins or complex lamellar forms, twin axis [111]
Cleavage[110] Perfect
FractureUneven to conchoidal
Mohs scale hardness3.5-4
LusterAdamantine, resinous, greasy
Streakbrownish white, pale yellow
DiaphaneityTransparent to translucent, opaque when iron-rich
Specific gravity3.9 - 4.2
Optical propertiesIsotropic
Refractive indexnα = 2.369 ZnS
Other characteristicsnon-radioactive, non-magnetic, Fluorescent and triboluminescent.
References[1][2][3]