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Formula: Ca2Co(AsO4)2.2H2O
Hydrated normal arsenate, roselite group, forms a solid solution with
wendwilsonite, cobalt-bearing mineral
Roselite-beta is the triclinic paramorph of roselite, which is monoclinic
Specific gravity: 3.46 to 3.74
Hardness: 3½
Streak: White to pale pink
Colour: Rose-red, pink; rose coloured in transmitted light
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 roselite-beta then
talmessite then acicular erythrite.
Associated with the series are hematite, calcite,
cobaltaustinite,
cobaltlotharmeyerite and rarely
spherocobaltite.
Roselite-wendwilsonite is commonly associated with
roselite-beta 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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