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Formula: Ca2Co(AsO4)2.2H2O
Hydrated normal arsenate,
roselite group, monoclinic
paramorph of triclinic
anorthoroselite, forms a solid solution with
wendwilsonite, cobalt-bearing mineral
Anorthoroselite is the triclinic paramorph of roselite, which
is monoclinic
Crystal System: Monoclinic
Specific gravity: 3.46 to 3.74 measured, 3.65 calculated
Hardness: 3½
Streak: White to pale pink
Colour: Rose-red, pink; rose coloured in transmitted light
Luminescence: Not fluorescent under UV
Solubility: Readily soluble in acids (Mindat)
Environments:
Roselite is a rare secondary mineral in
cobalt-bearing
hydrothermal mineral deposits
(HOM).
Localities
At the type locality, Rappold Mine, Saxony, Germany, roselite occurs in a
quartz vein,
associated with chalcedony
(Mindat).
Bou Azzer, Morocco, is the finest locality in the world for roselite group minerals. Here roselite is
associated
with talmessite
and erythrite
(HOM, Dana). The general sequence of crystallisation is: tabular
erythrite
and roselite then wendwilsonite and
anorthoroselite then
talmessite then acicular erythrite.
Associated with the series are hematite, calcite,
cobaltaustinite,
cobaltlotharmeyerite and rarely
spherocobaltite.
Roselite-wendwilsonite is commonly associated with
anorthoroselite or with cobalt-rich
talmessite.
Both minerals occur primarily
as drusy crusts in cavities; free standing crystals on dolomite or
quartz are rarer
(Minrec 38.5.389-393).
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