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Formula: K2Cu5Cl8(OH)4.2H2O
Oxyhalide
Crystal System: Monoclinic
Specific gravity: 3.03 , 3.066 calculated
Hardness: 3
Streak: Pale green
Colour: Green
Luminescence:
Solubility: Slowly decomposes in cold water and dissolves in dilute hydrochloric acid with no evolved gases
Melting point: At 900oC avdoninite melts and evaporates
Environments
Avdoninite is a product of precipitation from fumarolic gases at the type locality, and it is also reported as an
alteration on massive sulphide ore exposed at the Earth’s surface
(HOM).
Localities
At the type locality, the Yadovitaya fumarole, Second scoria cone, Northern Breakthrough, Great Fissure eruption, Tolbachik
volcano, Kamchatka Krai, Russia, avdoninite occurs among oxidation products of exhalative sediments. It comprises part
of cavity-lining crusts to several millimetres in thickness that have had access to air, but no direct contact with water.
Along with paratacamite, belloite and
langbeinite, it occurs as a replacement of
primary euchlorine, and
along with atacamite, as a constituent of
pseudomorphs after large crystals of
melanothallite. The avdoninite occurs as poorly formed,
short prismatic to thick tabular, bright green crystals to 0.2 mm
(AM 94.1075-1083).
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