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Formula: Sb2OS2
Sulphide
Crystal System: Triclinic
Specific gravity: 4.5 to 4.6 measured, 4.85 calculated
Hardness: 1 to 1½
Streak: Brownish red
Colour: Red
Environments:
Metamorphic environments
Hydrothermal environments
Kermesite is a secondary mineral that forms as an alteration of
stibnite, in
antimony deposits (Webmin).
The oxidation often continues changing kermesite to senarmontite
(AES).
Associated minerals include stibnite,
antimony, senarmontite,
valentinite, cervantite
and stibiconite
(HOM).
Localities
At the Lac Nicolet Antimony mine, Saints-Martyrs-Canadiens, Arthabaska RCM, Centre-du-Québec, Quebec, Canada, fine specimens of kermesite
have been found with crimson-red to maroon crystals to 5 cm, associated with valentinite,
native antimony, quartz and
stibnite. The mineralisation is hosted in
greenschist facies slate,
quartzite, phyllite and
serpentinite. Hydrothermal fluids invaded the country rocks and produced the
antimony-bearing quartz veins containing the various
mineral assemblages
(R&M 94.5.444-445).
At the Damingshan Mountain, Shanglin county, Guangxi, China, exceptional kermesite crystals were found in a single pocket,
associated with stibnite, valentinite,
senarmontite and very rarely
pääkkönenite
(Minrec 38.1.16).
At the Zhenwei (Zhenxu) antimony-gold deposit, Shanglin
county, Guangxi, China, kermesite occurs in the upper oxidation zone,
together with cervantite
(Minrec 38.1.15-16).
At the type locality, the Neue Hoffnung Gottes Mine, Bräunsdorf, Niederwiesa, Mittelsachsen, Saxony, Germany, kermesite occurs in
quartz vein vugs as sprays of small, lustrous red crystals associated with
stibnite, berthierite and
valentinite
(R&M 94.5.442)
At the Krížnica, Pernek, Malacky District, Bratislava Region, Slovakia, antimony mineralisation
is associated with
shale and phyllite. There were three stages of
ore formation, first quartz - pyrite -
arsenopyrite, then stibnite - carbonate -
quartz, and finally stibnite - kermesite. The
kermesite forms dark red radial aggregates to 6 cm together with stibnite,
valentinite, senarmontite,
schafarzikite and late-stage aragonite and
calcite
(R&M 94.5.444)
At the Kolársky vrch deposit, Pezinok, Pezinok District, Bratislava Region, Slovakia, kermesite forms excellent radial aggregates
of acicular crystals, rarely up to 14 cm, associated with stibnite,
valentinite, calcite, and
siderite
(R&M 94.5.444)
Herichová, Chyžné, Revúca District, Banská Bystrica Region, Slovakia, the first occurrence of kermesite associated with
valentinite and jamesonite was found on the
stockpile of the old tunnels. Other associated secondary minerals include
anglesite, cerussite,
gypsum, senarmontite,
scorodite and stibiconite. The radial aggregates
of kermesite are less than 1 cm across, bright red, and found in quartz vugs to 5 cm across
(R&M 94.5.444)
At the Globe and Phoenix mine, Kwekwe, Kwekwe District, Midlands, Zimbabwe, kermesite mineralisation was hosted in
quartz veins in talc - carbonate
schist and tonalitic
gneiss, associated with extensive alteration accompanied by muscovite varieties
sericite and fuchsite. The veins occur at the contact
between the Kwekwe ultramafic complex and granite
gneiss. This mine has produced some of the finest kermesite specimens known outside China
(R&M 94.5.440-446).
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