Category Sulfide mineral
Chemical formula (Zn,Fe)S
Strunz classification 02.CB.05a
Dana classification
Color Brown, yellow, red, green, black.
Crystal habit Euhedral Crystals - Occurs as well-formed crystals showing good external form. Granular - Generally occurs as anhedral to subhedral crystals in matrix. Colloform
Crystal system Isometric hextetrahedral (Àdàkọ:Overline 3m)
Twinning Simple contact twins or complex lamellar forms, twin axis [111]
Cleavage [110] Perfect
Fracture Uneven to conchoidal
Mohs scale hardness 3.5-4
Luster Adamantine, resinous, greasy
Streak brownish white, pale yellow
Diaphaneity Transparent to translucent, opaque when iron-rich
Specific gravity 3.9 - 4.2
Optical properties Isotropic
Refractive index nα = 2.369 ZnS
Other characteristics non-radioactive, non-magnetic, Fluorescent and triboluminescent.
References [1][2][3]