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Formula: Pb(Ga2Ge)(AsO>sub>4)2(OH)6
Arsenate, dussertite group,
alunite supergroup, gallium-
and germanium- bearing mineral
Crystal System: Trigonal
Specific gravity: 4.993 calculated
Hardness: 4
Streak: Pale yellow
Colour: Yellow
Solubility: Insoluble in dilute hydrochloric acid at room temperature
Environments
Karlseifertite is very rare, approved in 2024 and to date (December 2024) has been reported only from the type
locality.
Localities
The type locality, the Tsumeb Mine (Ongopolo Mine), Tsumeb, Oshikoto Region, Namibia, is an unusual site in that
germanium forms a
primary sulphide phase,
germanite. Although gallium is about
as abundant as yttrium or niobium in the
Earth’s crust, it only rarely forms distinct minerals and is typically found in low concentrations in sulphide minerals
such as sphalerite. Gallite is the
most widespread gallium mineral, with a total of nine reported localities. In
contrast, zincobriartite, the second most widespread
gallium mineral, is reported from only three localities. Of the eight valid
minerals with essential gallium, only
richardsite and
zincobriartite were not first discovered at Tsumeb, although
zincobriartite, but not
richardsite, has since been located there. Due to the very uncommon
elemental enrichment required to form karlseifertite, this mineral is expected to be extremely rare worldwide and
possibly may not be found anywhere except at Tsumeb
(AM 109.2173).
Karlseifertite from Tsumeb - Image
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