Rammelsbergite

• White nickel gravel

Rammelsbergite is a rarely occurring mineral from the mineral class of " sulfides and sulfosalts ". It crystallizes in the orthorhombic crystal system with the chemical composition NiAs2, thus contains nickel and arsenic in the ratio 1: 2

Rammelsbergite is opaque in any form and rarely makes good developed crystals with tabular to short prismatic habit from. He usually can be found in the form of granular to massive, radialstrahliger or fibrous mineral aggregates. Also crystal twins and pseudomorphs among others by native silver are known.

Fresh mineral samples are of zinnweißer color with a tinge to pink and have a strong metallic luster. By the time they are running on, however, and are dark. On the dash panel leaves Rammelsbergite a gray black stroke.

Special Features

With a Mohs hardness of 5.5 to 6 Rammelsbergite belongs to the medium-hard minerals that can be scratched with a steel file similar to the reference mineral orthoclase. On mechanical stresses he reacts but brittle and breaks with uneven shaped fracture surface.

Etymology and history

Rammelsbergite has been known for a long time, the mineral was first described in 1845 by Wilhelm Ritter von Haidinger. The type locality is located near snow mountain in the Ore Mountains. Is named the mineral after the German mineralogist Karl Friedrich Rammelsberg.

The mineral is recognized by the International Mineralogical Association, however, since the discovery before the foundation took place in 1959, led to the designation G for " Grandfathered ".

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the Rammelsbergite belonged to the department of " sulfides with the molar ratio of metal: S, Se, Te <1: 1", where he along with Costibit, Löllingite, Nisbit, Oenit, Safflorite and Seinäjokit the " Löllingitgruppe " with the system no. II/D.23 formed.

The 9th edition valid since 2001 and of the International Mineralogical Association (IMA ) used the Strunz'schen Mineral classification assigns the Rammelsbergite in the department of " metal sulfides with M: S ≤ 1: 2". However, this is further subdivided by the exact molar ratio and the conditions prevailing in the interconnect metals, so that the mineral according to its composition in the subdivision is to find "M: 2, with Fe, Co, Ni, PGE, etc.: S = 1" where it together with Anduoit, Klinosafflorit, Löllingite, Nisbit, Omeiit, rammelsbergite, Safflorite also the " Löllingitgruppe " with the system no. 2.EB.15a forms.

The mainly common in English-speaking classification of minerals according to Dana assigns the Rammelsbergite into the class of " sulfides and sulfosalts " and there in the department of " sulfide minerals ." Here he is the only member / together with the " Markasitgruppe ( Orthorhombic: Pnnm ) " with the system no. 02:12:02 within the subdivision " sulfides - tellurides and selenides, including - with the composition AmBnXp, with (m n): p = 1: 2" to find.

Modifications and varieties

The connection NiAs2 is dimorphic and is found in nature in addition to the orthorhombic crystallizing Rammelsbergite still as cubic crystallizing Krutovit and as also orthorhombic, but in a different space group, crystallizing Pararammelsbergit ago.

Education and Locations

Rammelsbergite forms as a secondary mineral in hydrothermal veins at intermediate temperatures. Along with this, other nickel -cobalt minerals are formed. Accordingly, the mineral is often associated with skutterudite on, but is also found along with Algodonit, Domeykite, Löllingite, Nickeline, Safflorite and uraninite and native bismuth and silver. Weathering the mineral has occasionally a coating of green Annabergite.

As a rather rare mineral formation Rammelsbergite can indeed be abundant in part to different sites, overall it is not very common. So far (as of 2013) are around 200 localities known as.

In Germany, among other localities lie in the Ore Mountains, Harz, the Black Forest and in the Mansfeld region. Other European countries with Rammelsbergite - finds are Austria ( among others Lölling in Carinthia), Czech Republic, France, Greece, Italy, Spain and the UK.

Outside Europe, one finds Rammelsbergite especially in North America (United States, Canada).

Crystal structure

Rammelsbergite crystallized orthorhombic with space group Pnnm ( Raumgruppen-Nr. 58) and the lattice parameters a = 4.76 Å; b = 5.80 Å and c = 3.54 Å and two formula units per unit cell.