Sulphosalt, thallium- and arsenic- bearing mineral
Specific gravity: 4.51
Streak: Deep red
Bernardite occurs in hydrothermal veins in
thallium-arsenic deposits. Common
associates include edenharterite,
stalderite and wallisite
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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