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Formula: Fe2+Ge(OH)6
Germanium-bearing hydroxide,
stottite subgroup
Crystal System: Tetragonal
Specific gravity: 3.596 measured, 3.54 calculated
Hardness: 4½
Streak: Grey-white
Colour: Brown
Environments:
Stottite is very rare, with the highest concentration of germanium of any known
mineral
(AM 43.1006-1008).
The type locality is the Tsumeb Mine, Oshikoto Region, Namibia, and this is the only known locality to date (September 2019).
Stottite is a secondary mineral formed in the oxidised zone of a
germanium-rich
dolostone-hosted hydrothermal polymetallic ore deposit
(Webmin, HOM).
It is formed in the deep oxidised orebody, at a depth of about 1000 metres, by the action of circulating water on
renierite and germanite
(Dana).
Stottite typically occurs in small cavities in partly oxidised massive sulphide ores that are enriched in
germanium. The sulfide
matrix of the type specimen comprises a mixture of renierite and
germanite with bornite,
tennantite and chalcocite.
In several other specimens stottite is associated with other secondary
minerals, including smithsonite, zinc-rich
siderite,
brunogeierite, schneiderhöhnite and
ludlockite.
Renierite and, possibly, leiteite are also part
of this paragenesis.
Leiteite, ludlockite,
renierite, and schneiderhöhnite are
all arsenites, in which arsenic occurs in its intermediate As(III) oxidation state. The occurrence of stottite in association
with arsenites suggests that the paragenesis and, by implication, stottite itself, form under relatively reducing conditions
(R&M 90.5.440-443).
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