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Formula: CaCo(CO3)2
Carbonate, dolomite group,
cobalt-bearing mineral
Crystal System:
Specific gravity: 3.140 calculated based on the empirical formula
Hardness: 3½ to 4
Streak: White
Colour: Pale to bright pink
Luminescence: Not fluorescent under either short wave or long wave UV
Environments
Škáchaite is a new mineral, approved in 2023 and to date (November 2024) reported only from the type locality.
Localities
At the type locality, the B117 hydrothermal vein, Uranium Mine No. 6, Brod, Příbram, Příbram District, Central Bohemian
Region, Czech Republic, škáchaite has been found in samples at a depth of 250 to 300 m below the surface. The
holotype polished section was taken from a museum specimen with dimensions 45 × 42 × 13 cm, which represents the
complete profile through a 22 cm thick symmetrical vein filling, also including surrounding rock. This unique sample of
bonanza-type silver mineralisation contains abundant elongated
native silver aggregates up to 6 cm in length in
gangue formed by various types of carbonates:
calcite, siderite,
spherocobaltite, ankerite,
kutnohorite, minrecordite and
members of the dolomite–škáchaite
series. Other associated minerals are safflorite,
löllingite,
cobaltpentlandite, the cobalt
analogue of heazlewoodite,
siegenite, carrollite,
mckinstryite, jalpaite,
chalcocite,
tetrahedrite-(Zn),
argentotetrahedrite-(Fe), IMA2023-126,
hematite, sphalerite,
galena, chalcopyrite,
pyrite and hisingerite.
Škáchaite is of low-temperature hydrothermal origin, and occurs as anhedral grains up to 50 μm in size and growth
zones in škáchaite–dolomite zoned crystals with thickness up to 100 μm
but usually only 5 to 20 μm. Škáchaite is pale to bright pink in colour; tiny fragments are translucent; it has a
white streak and vitreous lustre
(MM 88.255–261).
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