Oregonite

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Oregonite
Oregonite-Awaruite-642275.jpg
Oregonite and Awaruit from the type locality Josephine Creek, Oregon, USA (size: 11 mm × 4 mm × 5 mm)
General and classification
chemical formula FeNi 2 As 2
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.AB.20 ( 8th edition : II / B.12)
05/02/04/01
Crystallographic Data
Crystal system hexagonal
Crystal class ; symbol not defined
Lattice parameters a  = 6.083  Å ; c  = 7.130 Å
Formula units Z  = 3
Physical Properties
Mohs hardness 5
Density (g / cm 3 ) calculated: 6.92
Cleavage Please complete!
colour white in polished sections
Line color Please complete!
transparency opaque
shine Metallic luster

Oregonite is a very rare mineral from the mineral class of " sulfides and sulfosalts ". It crystallizes in the hexagonal crystal system with the composition FeNi 2 As 2 , so from a chemical point of view it is a nickel-iron arsenide , which up to now could only be found in the form of fine-grained pebbles up to about 0.5 mm in size with a smooth, brown crust.

Etymology and history

Oregonite was first discovered at Josephine Creek in Josephine County in the US state of Oregon and described in 1959 by Paul Ramdohr and Margaret Schmitt , who named the mineral after the state of Oregon.

classification

In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , oregonite belonged to the mineral class of "sulfides and sulfosalts" and there to the department of "sulfides with the molar ratio of metal: sulfur, selenium, tellurium> 1: 1", where he together with Heazlewoodite , Laflammeit , parkerite , Rhodplumsit and shandite formed a distinct group.

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns oregonite to the class of "sulfides and sulfosalts" and there to the department of "alloys and alloy-like compounds". However, this division is further subdivided according to the predominant metals in the compound, so that the mineral can be found according to its composition in the sub-division “Nickel-Semimetal Alloys”, where it is the only member of the unnamed group 2.AB.20 .

The systematics of minerals according to Dana also assigns oregonite to the class of "sulfides and sulfosalts" and there into the category of "sulfide minerals". Here he is the only member of the unnamed group 02.05.04 within the subdivision " 02.05 Sulphides - including selenides and tellurides - with the composition AmBnXp, with (m + n): p = 3: 2 ".

Crystal structure

Oregonite crystallizes isotypically with Heazlewoodite in the hexagonal crystal system (the space group has not yet been determined in detail) with the lattice parameters a  = 6.083  Å and c  = 7.130 Å as well as 3 formula units per unit cell .

Education and Locations

Oregonite forms in clinochlor and serpentines . Accompanying minerals include bornite , chalcopyrite , chromite , molybdenite and solid copper .

So far (as of 2011) oregonite could be detected in less than 10 locations. In addition to its type locality Josephine Creek in the US state of Oregon, the "Alexo Mine" near Dundonald in the Cochrane District in Canada, the "Skouriotissa Mine" near Skouriotissa in the Nicosia district in Cyprus, Ferrières-sur-Sichon in the French department Allier , Allchar in the Macedonian district of Roszdan and on the Chirynaisky massif in the Koryak mountains on the Russian peninsula of Kamchatka .

See also

literature

Web links

Commons : Oregonite  - collection of pictures, videos and audio files

Individual evidence

  1. ↑ a b c IMA / CNMNC List of Mineral Names - Oregonite (English, PDF 1.8 MB)
  2. ↑ a b Webmineral - Oregonite (English)