Formula: NiSbS
Sulphide, cobaltite group, forms a series with willyamite
Specific gravity: 6.65
Hardness: 5 to 5½
Streak: Black, greyish black
Colour: Tin-white, steel grey

Hydrothermal environments

Ullmannite is a nickel antimony sulphide that occurs in hydrothermal veins, associated with nickeline, gersdorffite, pentlandite, chalcopyrite, pyrrhotite, galena, tetrahedrite and dyscrasite (HOM).

The type locality is the Storch und Schöneberg Mine, Gosenbach, Siegen, Siegerland, North Rhine-Westphalia, Germany

At Brownley Hill, Cumbria, England, UK, ullmannite has been found as a primary mineral on galena and associated with bottinoite, cerussite and sulphur (MinRec 31.3.248).

Common impurities: Fe,Co,As,Bi

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