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Formula: Ga(OH)3
Hydroxide of gallium,
söhngeite subgroup
Specific gravity: 3.84 measured
Hardness: 4 to 4½
Colour: Brown, white, pale yellow, pale brown, pale greenish yellow
Environments
Sedimentary environments
Hydrothermal environments
Söhngeite is a rare mineral; although it was approved in 1965, to date (July 2022) it has been reported only
from the type locality.
Localities
At the type locality, the Tsumeb Mine, Tsumeb, Oshikoto Region, Namibia, söhngeite generally forms aggregates
on oxidising massive sulphide ore (galena,
chalcocite, sphalerite) that
is enriched in germanium and
gallium, usually with significant content of
germanite, renierite and
gallite. It is an alteration product of
gallite-bearing germanite in an
oxidation zone of a dolostone-hosted hydrothermal polymetallic ore
deposit, and forms crystalline, twinned groups and aggregates, up to 1 cm in size; single crystals are very rare.
Associated minerals include germanite,
gallite, calcite,
quartz, siderite and
tsumgallite
(R&M 97.2.183, HOM, Mindat).
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