Ullmannite

Discovered in 1843; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

NiSbS

Nickel Antimony Sulfide

Molecular Weight:

212.51 gm

Composition:

Nickel

27.62 %

Ni

Antimony

57.29 %

Sb

Sulfur

15.09 %

S

100.00 %

Classification

Mineral Classification:

Sulfides and Sulfosalts

Strunz 8th Ed. ID:

2/D.18-40

Nickel-Strunz 10th Ed. ID:

2.EB.25

2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
E : Metal Sulfides, M: S <= 1:2
B : M:S = 1:2, with Fe, Co, Ni, PGE, etc.

Related to:

Cobaltite Group. Ullmannite-Willyamite Series.

Members of Group:

Cobaltite Group: Changchengite, Cobaltite, Gersdorffite, Hollingworthite, Irarsite, Jolliffeite, Kalungaite, Maslovite, Mayingite, Michenerite, Milotaite, Padmaite, Platarsite, Testibiopalladite, Tolovkite, Ullmannite, Willyamite 

Varieties:

None

Synonyms:

Antimonikel (of Beudant), Antimon-nickel (of Beudant), Hartmannite, Nickelspiesglaserz, Nickel-stibine

Crystal Data

Crystallography:

Isometric - Tetartoidal

Crystal Habit:

As cubes and, less commonly, octahedra, pyritohedra, tetrahedra, to 3 cm. Cube faces striated by [110], twin boundaries of enantiomorphs.

Twinning:

Forms penetration twins about [110] with {001} the approximate composition plane; re-entrants develop on cube edges.

Physical Properties

Cleavage:

Perfect on {001}

Fracture:

Irregular/Uneven

Tenacity:

Brittle

Moh's Hardness:

5.0 - 5.5; Vickers: VHN₁₀₀=592-627 kg/mm²

Density:

6.65 - 6.85 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Steel-gray to silver-white; white in reflected light

Transparency:

Opaque

Luster:

Metallic

Refractive Index:

R: (400) 52.0, (420) 51.0, (440) 50.0, (460) 49.0, (480) 48.2, (500) 47.4, (520) 46.7, (540) 46.1, (560) 45.7, (580) 45.5, (600) 45.5, (620) 45.6, (640) 46.0, (660) 46.4, (680) 47.0, (700) 47.6

Birefringence:

0.000 (opaque)

Dispersion:

None

Pleochroism:

None

Anisotropism:

Individuals may be weakly anisotropic revealing a fine lamellar structure.

Occurances

Geological Setting:

With nickel minerals in hydrothermal veins.

Common Associations:

Nickeline, Gersdorffite, Pentlandite, Chalcopyrite, Pyrrhotite, Galena, Tetrahedrite, Dyscrasite

Common Impurities:

Fe, Co, As, Bi

Type Locality:

Storch und Schöneberg Mine, Gosenbach, Siegerland, North Rhine-Westphalia, Germany

Year Discovered:

1843

View mineral photos:

Ullmannite Mineral Photos and Locations

Unusual Gem Categories

Metallic Gems

More Information

Mindat.org
Webmineral.com

Ullmannite is a rare nickel antimony sulfide mineral and a member of the Cobaltite Group of minerals that also includes Cobaltite and Gersdorffite among others. Ullmannite has a steel-gray to silver-white color and metallic luster with a Mohs hardness of 5.0 - 5.5. It is very similar to the nickel arsenic sulfide called Gersdorffite. Gersdorffite's formula is NiAsS compared to Ullmannite's formula of NiSbS. Gersdorffite's formula shows the substitution of arsenic (As) for the antimony (Sb) in Ullmannite's formula, although Ullmannite usually has some arsenic in its chemistry. Ullmannite is rarer than Gersdorffite but the two minerals are almost indistinguishable from each other by ordinary evaluation means.

Ullmannite was named after Johann Christoph Ullmann (1771-1821), German mineralogist and chemist. Ullmann is considered to be one of the fathers of systematic mineralogy. Ullmann established a mineral collection (now the basis for the internationally renowned Museum of Mineralogy in Marburg) and authored Ein Systematisch Tabellarische Übersicht der Mineralogisch einfachen Fossilien, one of the first attempts to provide a structured organization to the observed minerals of the day.

Ullmannite distribution: in Germany, in North Rhine-Westphalia, from Freusburg at the Friedrich mine, near Wissen; the Petersbach mine, near Eichelhardt; Gosenbach; Salchendorf; and at Ramsbeck; in the Harz Mountains, from Neudorf; and elsewhere From Lölling, Carinthia, Austria. In France, at Ar, near Eaux-Bonnes, Pyrénées-Atlantiques. From Monte Narba and Masaloni, Sarrabus, Sardinia, Italy. In the Settlingstones mine, Fourstones, Northumberland, and at New Brancepeth colliery, Durham, England. From the Talnakh area, Noril’sk region, western Siberia, Russia. In the Esperanza mine, Salta Province, Argentina. In Canada, at the Kerr Addison mine, Timiskaming district, Ontario; and from the Nicholson mine, near Goldfields, Saskatchewan. At Broken Hill, New South Wales, Australia. In the Champion Reef mine, Kolar Gold Fields, Karnataka, India. Dozens of additional minor localities are known.

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