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Formula: Cu4Al3(OH)14F3.2H>2O
Fluoride, cyanotrichite group
Crystal System: Monoclinic
Specific gravity: 2.84 measured, 3.00 calculated
Hardness: 2½
Streak: Light blue
Colour: Light blue or bright sky-blue
Environments
Localities
At the type locality, the Khaidarkan Sb-Hg deposit, Batken Region, Kyrgyzstan, khaidarkanite has been found in
the oxidation zone; it forms needle-like crysta1s and their aggregates, associated with
calcite, quartz,
baryte, fluorite,
malachite, cupro-allophane,
conichalcite and chrysocolla
(Zapiski Vserossijskogo Mineralogicheskogo Obshchestva 128.3.58-63).
At Great Sleddale, Muker, Richmondshire, North Yorkshire, England, UK, khaidarkanite is derived from highly
oxidised, copper-bearing,
fluorite-rich veinstone at remote trial workings. It is undoubtedly of
supergene origin and appears to have formed in preference to
the more common cyanotrichite due to the presence of
primary fluorite,
which provided the necessary fluorine ions during oxidation of the veinstone
(Proceedings of the Yorkshire Geological Society 62.2.142–146).
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