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Formula: Co2+Co3+2O4
Oxide of cobalt,
spinel subgroup
Crystal System: Isometric
Specific gravity: 6.003 calculated
Hardness: 6 to 6½
Streak: Black
Colour: Dark grey
Environments
Guite is a comparatively new mineral, approved in 2017 and to date (January 2023) reported only from the type
locality.
Localities
At the type locality, the Sicomines copper-cobalt project, Kolwezi mining district, Lualaba, DR Congo, dark grey
guite
occurs as a granular agglomerate, 50 to 500 μm in size, and is associated closely with
heterogenite in a quartz matrix.
The copper–cobalt ores are hosted in a
formation that is composed of red and grey–green sandstone and
mudstone (R1 group),
dolostone and dolomitic
sandstone (R2 group) and
dolomitic siltstone and
mudstone (R3 group). The
cobalt-bearing dolomite in the R2
group is considered to be the source of cobalt. The samples were taken from the
drilling cores in the R2 group.
Guite is supposed to be a supergene
cobalt oxide formed from the precipitation of a
cobalt-bearing solution at weakly alkaline and oxidising conditions:
3Co(HCO3)2 + ½O2 + 12OH– → Co3O4 +
6CO2–3 + 9H2O
(MM 86.2.346-353).
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