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Formula: Ca5(AsO3OH)2(AsO4)2.9H2O
Hydrated hydrogen arsenate,
paramorph
of guérinite
Crystal System: Triclinic
Specific gravity: 2.63 measured, 2.60 calculated
Streak: White
Colour: Colourless to white
Luminescence: Not fluorescent in UV
Solubility: Dissolves readily in dilute hydrochloric acid
Environments
Ferrarisite dehydrates very slowly in dry air at room temperature and turns from colourless to white
(Mindat).
Localities
At the type locality, the Gabe Gottes mine, Sankt Jakob vein, Neuenberg, Ste Marie-aux-Mines, Colmar-Ribeauvillé,
Haut-Rhin, Grand Est, France, ferrarisite occurs in oxidised vein assemblages in the
arsenic-rich mine as a post-mine low-temperature reaction product of
carbonate gangue with arsenical
solutions derived from arsenic. The ferrarisite forms white radiating
very elongated crystals associated with picropharmacolite,
pharmacolite, sainfeldite,
rauenthalite, phaunouxite,
calcite and löllingite
(HOM, Mindat).
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