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Formula: Hg3S2Cl2
Chloride, paramorph of
kenhsuite and lavrentievite,
mercury-bearing mineral
Crystal System: Isometric
Specific gravity: 6.845 calculated
Hardness: 3
Colour: Light orange-pink, but becomes light grey to black on prolonged exposure to light
Environments
Volcanic igneous environments
Hydrothermal environments
Localities
At the Arzak Hg occurrence, Uyuk Range, Pi-Khem District, Tuva, Russia, corderoite occurs in the oxidised
hydrothermal deposit asssociated with cinnabar,
calomel, eglestonite,
arzakite, lavrentievite,
kuznetsovite, mercury,
quartz and kaolinite
(HOM).
At the type locality, the McDermitt mine, Opalite Mining District, Humboldt County, Nevada, USA, corderoite,
with or without cinnabar, occurs predominantly in playa sediments. The lake
sediments consist of clays (altered
tuff and ash) with lesser amounts of
agglomerate and small lenses of
chalcedony. The associated ore zone minerals are mainly pale green to
buff-coloured montmorillonite,
alpha quartz, cristobalite,
K-feldspar and plagioclase
feldspar.
Corderoite occurs in this zone as separate masses or as replacements and rims for
cinnabar, other associated minerals include
kleinite, kenhsuite,
radtkeite, montmorillonite,
quartz, cristobalite,
orthoclase and plagioclase.
Corderoite and cinnabar also occur within hydrothermally altered
rhyolitic breccia in
the main Cordero mine and nearby underground workings and surface pits.
The relative ease with which corderoite is formed under acid conditions, the presence of chlorine ions as a
common constituent of hot spring or groundwaters, and the relationships observed in the field suggest that
corderoite is a low temperature supergene mineral
(AM 59.652-655, HOM).
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