The Mineral rammelsbergite
Rammelsbergite belongs to the Loellingite group, which is a group of chemically related isomorphous minerals that are all rare. Other members discussed in this guide are Loellingite and Safflorite. Rammelsbergite was named after the German scientist K.F. Rammelsberg (1812-1899).
Color
Silver-white with a reddish tint. Tarnishes yellow or pink.
Crystal System
Orthorhombic
Properties
Streak
Gray |
Hardness
5.5 - 6 |
Transparency
Opaque |
Specific Gravity
6.9 - 7.1 |
Luster
Metallic |
Cleavage
None |
Fracture
Uneven |
Tenacity
Brittle |
Additional Information
Composition
Nickel arsenide, sometimes with some cobalt and iron. If the nickel (Ni) is replaced by more than 50% iron (Fe), the mineral is not Rammelsbergite, but Loellingite, and if it is replaced by more than 50% cobalt (Co), the mineral is Safflorite. |
In Group
Sulfides; Arsenides |
Striking Features
Color and tarnish, crystal habits |
Environment
In medium temperature cobalt and nickel veins. |
Rock Type
Sedimentary, Metamorphic |
Noteworthy Localities
Rammelsbergite is a rare mineral, and its localities are limited. Occurrences include Kongsberg, Norway; Ste Marie-aux-Mines, Alsace, France; Schneeberg, Saxony, Germany; Binntal, Switzerland; and Aït Ahmane, Bou Azzer, Morocco.
Rammelsberg was found in Mexico in the Silver mines of Batopilas, Chihuahua. In Canada it occurs in the Eldorado mine near the Great Bear Lake, Northwestern Territories, and in Cobalt, Timiskaming District, Ontario. In the U.S., Rammelsbergite was found in the Mohawk mine, Keweenaw Co., Michigan; and in the Trotter Dump, Franklin, Sussex Co., New Jersey.
Common Mineral Associations
Loellingite, Chloanthite, Silver
Distingushing Similar Minerals
Arsenopyrite - Difficult to distinguish, but contains sulfur attributes which are lacking in Rammelsbergite.
Skutterudite, Loellingite, and Safflorite - Indistinguishable without x-ray analysis.
Pyrite, Marcasite, and Pyrhottite - Occur in different crystals, more yellow in color.