Formula: Ag₅SbS₄

Species: Sulfosalts

Colour: Lead gray or black

Lustre: Metallic

Hardness: 2 – 2½

Specific Gravity: 6.26

Crystal System: Orthorhombic

Name: Named after the Austrian Mining Director/engineer and life-long mineral collector, Archduke Stephan Franz Victor von Habsburg-Lothringen (1817-1867).

Type Locality: Freiberg, Mittelsachsen, Saxony – Germany

A less common Ag-rich silver sulphosalt.