Rösslerite

minerals

pharmacolite

haidingerite

erythrite

Formula: Mg(AsO3OH).7H2O
Hydrated acid arsenate
Specific gravity: 1.943
Hardness: 2 to 3
Streak: White
Colour: Colourless to white, faint tints; colourless in transmitted light
Solubility: Readily soluble in dilute hydrochloric acid, slightly soluble in water
Environments

Hydrothermal environments

Rösslerite is a mineral occurring with other arsenates in the oxidised zone of arsenical ore deposits (Webmin, Dana), associated with pharmacolite, haidingerite, picropharmacolite and erythrite (HOM).

Localities

At Jachymov, Bohemia, Czech Republic, rösslerite occurs with pharmacolite and haidingerite (Dana).

At the type locality, "Im Lochborn" Copper mine, Bieber, Gelnhausen, Main-Kinzig, Hesse, Germany, rösslerite is associated with pharmacolite and erythrite (Mindat, Dana).

Alteration:

Rösslerite dehydrates in air to form brassite (Mindat).

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