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Collecting from the Tolbachik fumeroles is not for the faint-hearted. The fumerole temperature may be
500oC to 800oC, but the ambiant temperature may be as low as 10oC in summer, with
rain, or a daunting -30oC in winter, with snow that may last as long as six months. The latitude is just
short of 60o N (the Arctic Cicle is just over 66o N), and the highest point is at an altitude
of 3682 m (high enough to begin to feel its effect on your breathing). Nevertheless, standing on a rough
scree slope in these conditions, scientists have collected no fewer than 270 different mineral species, and for 133
of them this is the type locality.
Formula: K3Cu2+3AlO2(SO4)4
Anhydrous sulphate
Crystal System: Triclinic
Specific gravity: 3.1 measured, 2.95 calculated (HOM)
Hardness: 2 to 2½
Streak: Light green
Colour: Dark Green, turns white on exposure to air, possibly from hydration (HOM)
Environments
Alumoklyuchevskite was approved in 1993, but to date (July 2023) it has been reported only from the second
scoria cone of the Great Fissure eruption at Tolbachik, in three different fumeroles.
Localities
At the type locality, the Great Fissure eruption, Tolbachik Volcanic field, Milkovsky District, Kamchatka Krai,
Russia, alumoklyuchevskite is deposited by fumarolic gases as aggregates of prismatic to needle-like crystals,
up to 1 mm long and less than 0.1 mm thick. Associated minerals include
fedotovite, tenorite,
lammerite, averievite,
piypite and langbeinite
(HOM, Mindat).
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