Gersdorffite
Current inventory: 0 gems
 

  
Gersdorffite was named in 1845 by Alexander Löwe in honor of Johann Rudolf Ritter von Gersdorff (1781–1849), mining expert and owner of the Zinkwand nickel mine at Schladming, Styria, Austria where it was discovered.

Discovered in 1845; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

NiAsS 

Nickel Arsenic Sulfide

Molecular Weight:

165.68 gm

Composition:

Nickel

35.42 %

Ni

Arsenic

45.22 %

As

Sulfur

19.35 %

S

100.00 %

Classification

Mineral Classification:

Sulfides

Strunz 8th Ed. ID:

2/D.12-20

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. Polymorphism: Modifications -Pa3, -P213, and -Pca21 are known.

Members of Group:

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

Varieties:

Antimonian Gersdorffite, Cobaltoan Gersdorffite

Synonyms:

Amoibite, Disosmose, Dobschauite, Nickelarsenikglanz, Nickelarsenikkies, Nickelarsenkies, Nickelglanz, Plessite (of Dana)

Crystal Data

Crystallography:

Isometric (Cubic) - Tetartoidal

Crystal Habit:

Crystals are octahedral, typically modified by the cube, to 4 cm, or pyritohedral, may be striated as is pyrite; commonly internally zoned. 

Twinning:

None

Physical Properties

Cleavage:

Perfect on {100}

Fracture:

Irregular/Uneven

Tenacity:

Brittle

Moh's Hardness:

5.5; Vickers: VHN₁₀₀=657 - 767 kg/mm²

Density:

5.90 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Silver-white to steel-gray; may tarnish gray or grayish black; white in polished section. Color in reflected light: white. 

Transparency:

Opaque

Luster:

Metallic

Refractive Index:

R: (400) 50.2, (420) 49.7, (440) 49.1, (460) 48.6, (480) 47.7, (500) 47.0, (520) 46.2, (540) 45.7, (560) 45.3, (580) 45.1, (600) 45.0, (620) 45.1, (640) 45.3, (660) 45.5, (680) 45.9, (700) 46.3

Birefringence:

0.000 (Isotropic)

Dispersion:

n/a

Pleochroism:

n/a

Occurances

Geological Setting:

In hydrothermal vein deposits formed at medium temperatures.

Common Associations:

Nickeline, Nickel-Skutterudite, Cobaltite, Ullmannite, Maucherite, Löllingite, Platinum-group minerals, Millerite, Pyrite, Marcasite, Chalcopyrite

Common Impurities:

Fe, Co, Sb, Cu

Type Locality:

Zinkwand, Obertalbach valley, Schladminger Tauern, Schladming, Styria, Austria

Year Discovered:

1845

View mineral photos:

Gersdorffite Mineral Photos and Locations

Unusual Gem Categories

Metallic Gems

More Information

Mindat.org
Webmineral.com

Gersdorffite is a nickel arsenic sulfide mineral that is a member of the Cobaltite Group of minerals that alo includes Cobaltite and Ullmannite among others. Most members of this group are rare to extremely rare except for Cobaltite. Gersdorffite is often found associated with other metallic sulfide (or arsenide) minerals such as Chalcopyrite, Cobaltite, Marcasite, Nickeline, Pyrite and Skutterudite and some non-metallic, very colorful, minerals such as Annabergite and Erythrite. Gersdorffite is always opaque with a metallic luster and silver-white to steel-gray color that may tarnish to gray or grayish black or may appear white in polished section. Mineral specimens can be very attractive with the various associated minerals. Faceted Gersdorffite gems are very rare and can also be very attractive as in the gem pictured above with a vein of Annabergite running through it.

Gersdorffite was named in 1845 by Alexander Löwe in honor of Johann Rudolf Ritter von Gersdorff (1781–1849), mining expert and owner of the Zinkwand nickel mine at Schladming, Styria, Austria where it was discovered.

Gersdorffite distribution: a number of new localities have been recognized in recent years, only a few of which can be listed. In Austria, from Schladming, 64 km southeast of Salzburg, Styria [TL], and at Olsa, Freisach, Carinthia. In Germany, at Müsen, Wissen, and Ramsbeck, North Rhine-Westphalia; from Lobenstein, Thuringia; at Bad Ems and Dillenburg, Hesse; and from the Rammelsberg mine, near Goslar, and at Wolfsberg, Harz Mountains. From Dobšiná (Dobschau), Slovakia. In the Craignure mine, Inverary, Strathclyde region, Scotland. At Silvermines, County. Tipperary, Ireland. In the USA, large crystals from the Snowbird mine, Mineral County, Montana. In Canada, in several mines at Sudbury and Cobalt, Ontario. At Cochabamba, Bolivia. In the Aït Ahmane mine, 10 km east of Bou Azzer, Morocco, as fine crystals. From the Mt. Ogilvie and Nichol Nob mines, Flinders Ranges, South Australia.
 

  
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