Aschamalmite

aschamalmite

galena

cosalite

chlorite

Images

Formula: Pb6-3xBi2+xS9
Sulphosalt, lillianite homologous series group, bismuth-bearing mineral
Crystal System: Monoclinic
Specific gravity: 7.33 calculated
Hardness: 3½
Streak: Lead-grey
Colour: Lead-grey
Environments

Metamorphic environments
Hydrothermal environments

Aschamalmite is apparently only stable at temperatures below 350°C. Common associates include albite, calcite, chlorite group minerals, cosalite, galena, orthoclase and quartz (Mindat).

Localities

At the type locality, Ascham Alp - southeast of, Ascham Alp - Breitfuß - Sonntagskopf area, Neukirchen am Großvenediger, Zell am See District, Salzburg, Austria, aschamalmite is found in mineralised, alpine-cleft veins cutting through gneiss, associated with quartz, albite, adularia, calcite, chlorite and galena.
The aschamalmite occurs as lead-grey, lathlike crystals to 5 cm in length or thick, slightly bent plates up to 1 cm2. Most crystals are heavily altered to a mixture of bismutite and other as yet unidentified phases. Exsolution lamellae of galena and cosalite are commonly present (AM 69.810-815).

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