Guite

guite

heterogenite

cobalt

quartz

Images

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

Hydrothermal 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 coppercobalt 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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