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Formula: Mg(AsO3OH).4H2O
Hydrated arsenate
Crystal System: Orthorhombic
Specific gravity: 2.28 to 2.33 measured, 2.326 calculated
Streak: White
Colour: White
Luminexcence: Not fluorescent
Environments
Brassite is a rare reaction product of arsenic-rich solutions with
calcium-magnesium carbonates. Associated minerals include pharmacolite,
picropharmacolite, weilite,
haidingerite, rauenthalite,
arsenic, realgar and
dolomite
(HOM).
Brassite may occur also as a dehydration product of rösslerite
(Mindat).
Localities
At the type locality, Jáchymov, Karlovy Vary District, Karlovy Vary Region, Czech Republic, brassite occurs as white
crusts and coating on museum samples labelled rösslerite,
pharmacolite and haidingerite. In
addition to these minerals, the brassite is associated with arsenic,
weilite, rauenthalite and
picropharmacolite
(AM 60.945).
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