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Formula: Ca2Cu5Sb
Hydrated arsenate containing halogen
Crystal System: Monoclinic
Specific gravity: 3.2 to 3.3
Hardness: 2
Streak: Greenish blue
Colour: Turquoise-blue
Solubility: Readily soluble in 1:10 hydrochloric acid
Environments
Sedimentary environments
Hydrothermal environments
Localities
At Triembach-au-Val, Sélestat-Erstein, Bas-Rhin, Grand Est, France, richelsdorfite is associated with
erythrite, chalcophyllite,
cornwallite, strashimirite,
tetrahedrite–tennantite and
baryte
(HOM).
At the type locality, the Wilhelm mine, Nentershausen, Hersfeld-Rotenburg, Kassel Region, Hesse, Germany,
richelsdorfite was found in sandstone, associated with
calcite, duftite,
tyrolite and tetrahedrite, later it
was also found in cavities in baryte and as an incrustation on blocks of
copper shale. Richelsdorfite occurs mostly in very small speheroidal
aggregates up to 0.2 mm in diameter; rarely, tabular single crystals may attain 0.5 mm in size
(AM 69.211).
Richelsdorfite from the Wilhelm Mine -
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At the Samson Mine, St Andreasberg, Braunlage, Goslar District, Lower Saxony, Germany, richelsdorfite was found in
cavities in quartz with calcite,
tetrahedrite, galena,
brochantite and devilline
(AM 69.211).
At the Dolyhir Quarry, Old Radnor, Powys, Wales, UK, thin calcite-filled fractures in
limestone adjacent to the
lead-copper vein contained abundant
tennantite-(Zn), with baryte,
chalcopyrite, enargite,
galena and minor relict sphalerite. The
top of the vein exposure was very close to the original land surface and oxidation had produced a diverse assemblage of
secondary minerals including
azurite, copper,
cuprite, malachite,
mimetite, tyrolite and
zincolivenite.
Turquoise to sky-blue crystal aggregates of richelsdorfite were found on a small number of specimens.
The copper and arsenate ions required for
the supergene minerals to form are likely to have been released by the
oxidation of tennantite-(Zn). Calcium was almost certainly supplied by
calcite, which is ubiquitous in the fractures and surrounding
limestone. The antimony required
for richelsdorfite was probably also supplied by tennantite-(Zn) as no
other antimony-bearing primary
phases are present. There is sporadic substitution of antimony for
arsenic in tennantite-(Zn) from the main
vein and surrounding calcite-rich fractures
(JRS 23.33-38).
At the Gold Chain Mine, Mammoth, Tintic Mining District, Juab County, Utah, USA, richelsdorfite has been
found as fine flattened, chisel-shaped crystals that are pale blue to medium blue and usually occur as bundles in
vugs in granular quartz, almost always associated with
tyrolite and corroded enargite.
Richelsdorfite has also been found with azurite,
cornwallite, olivenite and
pyrite
(MinRec 55.2.220).
Richelsdorfite from the Gold Chain Mine -
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