Ferrarisite

ferrarisite

picropharmacolite

rauenthalite

phaunouxite

Images

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

Hydrothermal 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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