Neustädtelite

neustadtelite

cobaltneustadtelite

preisingerite

zeunerite

Images

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

Hydrothermal 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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