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Formula: Hg3OCl
Oxyhalide of mercury
Crystal System: Monoclinic
Specific gravity: 9.50 to 9.80 measured, 9.64 calculated
Hardness: 2 to 2½
Streak: Cherry to cinnabar red
Colour: Cherry red, darkening to dark red, purple
Solubility: Poyarkovite is instantly blackened by KOH, decomposed by nitric acid and does not react with hydrochloric acid
Environments
Volcanic igneous environments
Hydrothermal environments
Poyarkovite is a secondary mineral in the oxidised zone of
mercury deposits. Associated minerals include
eglestonite, calomel,
terlinguaite, montroydite,
kuznetsovite, shakhovite,
chursinite, corderoite,
mercury, cinnabar and
livingstonite
(HOM).
Poyarkovite is unstable when extracted from a primary place of "conservation", and it eventually transforms completely to
an X-ray-amorphous substance
(Mindat).
Localities
At the type locality, the Khaidarkan Sb-Hg deposit, Kadamjay District, Batken Region, Kyrgyzstan, poyarkovite
occurs in irregular grains and aggregates, usually in close contact with eglestonite
and calomel. Also present in the deposit are
terlinguaite, montroydite,
kuznetsovite, shakhovite,
corderoite, native mercury, and
hypogene cinnabar and
livingstonite
(AM 67.860).
Poyarkovite from Khaidarkan - Image
At the Arzak Hg occurrence (Arzakskoye), Uyuk Range, Pi-Khem District, Tuva, Russia,
mercury mineralisation is situated in hydrothermally altered
breccia of
rhyolite-dacite
poryhyry. The main primary
mercury mineral is cinnabar; also there are
local occurrences of cadmium-rich
metacinnabar and cadmium- and
mercury- rich sphalerite.
Poyarkovite is found within the brecciated
rhyolite-dacite
poryhyry in small cavities lined with
primary cinnabar.
Poyarkoviteis closely associated with the following supergene minerals:
(1) crystalline aggregates, individual rhombododecahedral or needle-shaped crystals of
eglestonite
(2) crystalline grains of calomel and
terlinguaite
(3) montroydite and native mercury.
Except for native mercury, which fills the central parts of the cavities, these minerals
are sporadically present on masses of cinnabar as thin crusts.
Eglestonite and calomel are the predominant
mercury chlorides.
Poyarkovite is very rare. It forms small irregular grains up to 0.3 mm in diameter in
eglestonite or calomel aggregates and as
sporadic minute, free-growing crystals on the surface of cinnabar grains. Other
secondary minerals of mercury
discovered in the Arzak oxidized ores include bromine-rich corderoite,
lavrentievite, arzakite,
grechishchevite, kuznetsovite and
schuetteite. All these minerals are present in various associations without
poyarkovite
(CM 37.119-126).
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