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Formula: Bi2Fe3+(Fe3+,Co)2(O,OH)4(AsO4)2
Arsenate, bismuth- and
cobalt- bearing mineral
Crystal System: Triclinic
Specific gravity: 5.81 calculated
Hardness: 4½
Streak: Light brown
Colour: Brown, brown-red, black
Luminescence: Not fluorescent under UV
Solubility: Completely soluble in warm, dilute hydrochloric acid without effervescence
Environments
Neustädtite occurs in vugs in quartz collected on mining waste
piles. Associated minerals include cobaltneustädtelite,
quartz, preisingerite,
limonite/goethite,
mixite, zeunerite,
bismutite and
bismutoferrite
(HOM).
Localities
The type locality is the Güldener Falk Mine, Neustädtel, Schneeberg, Erzgebirgskreis, Saxony, Germany.
Neustädtelite and cobaltneustädtelite have been found
at several mine dumps in the Schneeberg area, as well as in the vicinity of Schneeberg-Neustädtel. The specimens
containing neustädtelite and cobaltneustädtelite
consist mainly of coarse quartz; neustädtelite and
cobaltneustädtelite are crystallised in small vugs in
association with preisingerite, powdery
limonite/goethite, and rarely
with mixite, zeunerite and
bismutite. The joint occurrence of
neustädtelite/cobaltneustädtelite together with
preisingerite seems to be characteristic.
Preisingerite forms tiny lustrous nodular aggregates as well as
dull, seemingly decomposed, but still crystalline masses and aggregates. These crystalline masses are frequently
overgrown by well developed
neustädtelite/cobaltneustädtelite crystals
(AM 87.5.726-738).
Neustädtelite from the Güldener Falk Mine -
Image
At Friedensgrube, Lichtenberg, Hof District, Upper Franconia, Bavaria, Germany, an occurrence of
neustädtelite has been confirmed in dump material of the Friedrich-Wilhelm adit, where it forms nearly black
crystalline crusts and aggregates, associated with bismuth and
bismutoferrite. This material is very close to the end-member
composition of neustädtelite
(AM 87.5.726-738).
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