Bernardite

bernardite

edenharterite

erniggliite

hatchite

Images

Formula: TlAs5S8
Sulphosalt, thallium- and arsenic- bearing mineral
Specific gravity: 4.51
Hardness: 2
Streak: Deep red
Colour: Black
Environments

Hydrothermal environments

Bernardite occurs in hydrothermal veins in thallium-arsenic deposits. Common associates include edenharterite, erniggliite, hatchite, hutchinsonite, lorándite, orpiment, realgar, stalderite and wallisite (Mindat).

Localities

At the type locality, Allchar, Rožden, Kavadarci Municipality, North Macedonia, bernardite occurs in the thallium-bearing deposit with realgar and orpiment. It forms black, thick-tabular crystals that are typically less than 1 mm, but up to 4 mm in size; faces are dull, partly corroded and striated (AM 75.1209).

At the Lengenbach Quarry, Fäld, Binn, Goms, Valais, Switzerland, bernardite occurs in a hydrothermal deposit with other arsenic-thallium sulphides. Associated minerals include realgar, orpiment, hutchinsonite, wallisite, hatchite, lorándite, edenharterite, erniggliite and stalderite (HOM).

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