Sulphur

anhydrite

cinnabar

Formula: S
Native element
Specific gravity: 2.0 to 2.1
Hardness: 2
Streak: White
Colour: Yellow, brownish yellow, greenish yellow

With a low melting point of 113 degrees C, sulphur burns readily in air, with a low blue flame, and gives off choking fumes of sulphur-dioxide - acrid odor (forms sulphurous and eventually sulphuric acid in air).
Solubility: Insoluble in water, hydrochloric, nitric and sulphuric acid
Environments:

Sedimentary environments
Volcanic sublimates (common)

Most native sulphur is formed by reduction of sulphates, especially in salt domes, where it forms by the bacterial decomposition of calcium sulphate. It also often occurs at or near the crater rims of active or extinct volcanoes, derived from volcanic gases and associated with realgar and cinnabar. The volcanic gases may produce sulphur as a direct sublimation product or by the incomplete oxidation of hydrogen sulphide gas. In sedimentary rocks sulphur is most commonly associated with anhydrite, gypsum and limestone.

At the Ball Eye mine and quarry, Cromford, Derbyshire, England, UK, native sulphur has been reported with anglesite in oxidised galena (RES p74).

At Tsumeb, Namibia, sulphur has been found with schultenite, anglesite and galena (R&M 93.6.548).

At Cookes Peak mining district, Luna county, New Mexico, USA, sulphur is found in small cavities in oxidising galena (R&M 94.3.236).

Alteration

chalcopyrite, arsenopyrite, CO2 and O2 to Fe-tennantite, siderite and sulphur
10CuFeS2 + 4FeAsS + 4CO2 + 8O2 → Cu10Fe2As4S13 + 4Fe(CO3) + 11/2S2
(CM 28.725-738)

chalcopyrite, arsenopyrite and sulphur to Fe-tennantite and pyrite
10CuFeS2 + 4FeAsS + 13/2S2 → Cu10Fe2As4S13 + 12FeS2
This reaction occurs at a comparatively low temperature (CM 28.725-738).

chalcopyrite, arsenopyrite and sulphur to Fe-tennantite and troilite
l0CuFeS2 + 4FeAsS + l/2S2 → Cu10Fe2As4S13 + l2FeS
(CM 28.725-738)

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

covellite and ferric sulphate to ferrous sulphate, copper sulphate and sulphur
CuS + Fe2(SO4)3 → 2FeSO4 + CuSO4 + S
Covellite may be oxidised by the strong oxidising agent ferric sulphate according to the above reaction to form sulphur (AMU/b3-3-7.htm).

enargite and pyrite to Fe-tennantite, chalcopyrite and sulphur
4Cu3AsS4 + 4FeS2 → Cu10Fe2As4S13 + 2CuFeS2 + 7/2S2
(CM 28.725-738)

skinnerite to chalcocite, antimony and sulphur
2Cu3SbS3 → 3Cu2S + 2Sb + 3/2S2
(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 chalcocite, antimony, sphalerite and sulphur
Cu10Zn2Sb4S13 → 5Cu2S + 4Sb + 2ZnS + 3S2
(CM 28.725-738)

Zn-tetrahedrite to skinnerite, antimony, sphalerite and sulphur
3Cu10Zn2Sb4S13 → 10Cu3SbS3 + 2Sb + 6ZnS + 3/2S2
(CM 28.725-738)

Common impurities: Se,Te

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