Gersdorffite
Gersdorffite is a nickel arsenic sulfide mineral that is a known member for the Cobaltite Group of minerals that alo includes Cobaltite and Ullmannite among others. Most members of this combined group are unusual to extremely rare except for Cobaltite. Gersdorffite is often found connected with other sulfide that is metallicor arsenide) minerals such as for example Chalcopyrite, Cobaltite, Marcasite, Nickeline, Pyrite and Skutterudite and some non-metallic, very colorful, minerals such as Annabergite and Erythrite. Gersdorffite is often opaque with a luster that is metallic silver-white to steel-gray color that may tarnish to gray or grayish black colored or may appear white in polished section. Mineral specimens can be very attractive with the different associated minerals. Faceted Gersdorffite gems are extremely unusual and that can be very appealing like in the gem pictured above with a vein of Annabergite running through it.
Gersdorffite ended up being named in 1845 by Alexander Löwe in honor of Johann Rudolf Ritter von Gersdorff (1781–1849), mining expert and owner of this Zinkwand nickel mine at Schladming, Styria, Austria where it had been discovered.
Gersdorffite circulation: a genuine amount of brand new localities have already been recognized in recent years, just a few of that can easily 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 through the Rammelsberg mine, near Goslar, and at Wolfsberg, Harz Mountains. From Dobšiná (Dobschau), Slovakia. Into the Craignure mine, Inverary, Strathclyde area, Scotland. At Silvermines, County. Tipperary, Ireland. Within 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 eastern of Bou Azzer, Morocco, as fine crystals. From the Mt. Ogilvie and Nichol.
| 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 % |
| 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 |
| 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 |
| 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 |
