Stibnite

stibnite

cinnabar

antimony

galena

Images

Formula: Sb₂S₃
Sulphide, stibnite group, antimony-bearing mineral
Crystal System: Orthorhombic
Specific gravity: 4.63 measured, 4.625 calculated
Hardness: 2
Streak: Dark grey
Colour: Lead-grey
Solubility: Moderately soluble in hydrochloric acid; slightly soluble in nitric acid
Melting point: 546^oC
Environments:

Hot spring deposits
Hydrothermal environments common

Stibnite is found in epithermal (low temperature) hydrothermal veins, particularly in stibnite- quartz veins, in replacement deposits and in hot spring deposits. It is associated with other antimony minerals that have formed as the product of its decomposition, and with galena, cinnabar, sphalerite, baryte, realgar, orpiment and gold.

At Schemnitz, Slovakia, stibnite occurs with stibiconite (FM OP33).

At Wet Swine Gill, Coombe Height, Caldbeck, Allerdale, Cumbria, England, UK, stibnite occurs as tiny glittery silver specks on a quartz matrix, with specks of a yellow mineral that is possibly orpiment (AESS).

Alteration

chalcopyrite, stibnite and sulphur to Fe-tetrahedrite and pyrite
10 CuFeS₂ + 2 Sb₂S₃ + 3/2 S₂ → Cu₁₀Fe₂As₄S₁₃ + 8FeS₂
(CM 28.725-738)

stibnite and pyrite to berthierite and sulphur
Sb₂S₃ + FeS₂ → FeSb2S4 + l/2S₂
(CM 28.725-738)

Fe-tetrahedrite, berthierite and sulphur to chalcopyrite and stibnite
Cu₁₀Fe₂Sb₄S₁₃ + 2FeSb₂S₄ + 11/2S₂ → 10CuFeS₂ + 4Sb₂S₃
(CM 28.725-738)

Fe-tetrahedrite, siderite and sulphur to chalcopyrite, stibnite, CO₂ and O₂
Cu₁₀Fe₂Sb₄S₁₃ + 8Fe(CO₃) + 13/2S₂ → 10CuFeS₂ + 2Sb₂S₃ + 8CO₂ + 4O₂
(CM 28.725-738)

Zn-tetrahedrite to skinnerite, stibnite and sphalerite
3Cu₁₀Zn₂Sb₄S₁₃ → 10Cu₃SbS₃ + Sb₂S₃ +6ZnS
(CM 28.725-738)

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