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Formula: Ca2Mg(AsO4)2.2H2O
Valence: Ca2Mg(As5+O4)2.2H2O
Hydrated normal arsenate,
roselite group
Forms a series with roselite
Crystal System: Monoclinic
Specific gravity: 3.52 measured, 3.478 calculated
Hardness: 3 to 4
Streak: Pale pink
Colour: Pale pink to red
Common impurities: Co
Environments:
Wendwilsonite is a rare secondary mineral in cobalt-bearing
hydrothermal mineral deposits. There are two
type localities, Sterling Hill mine, New Jersey, USA and Arhbar mine, Bou Azzer, Morocco.
Localities
At Coahuila, Mexico, a sample of wendwilsonite crystals on calcite has been found
(AM 72.217-221).
At the Arhbar mine, Bou Azzer, Morocco, wendwilsonite is associated with
talmessite and
erythrite on altered ore and
calcite gangue
(Dana, HOM, AM 72.217-221).
The common paragenesis, where a sequence is visible, consists of erythrite,
followed by wendwilsonite or roselite, followed by
talmessite, and possibly a second generation of
erythrite
(AM 72.217-221).
Wendwilsonite from Bou Azzer -
Image
At the Sterling Hill mine, New Jersey, USA, wendwilsonite occurs as 0.5 mm crystals with
calcite crystals on
serpentine which encrusts manganoan calcite
with very sparse franklinite and willemite.
Wendwilsonite is very rare at this locality
(Dana, AM 72.217-221).
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