Aurorite

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Aurorite
Aurorite in calcite with pyrolusite Hydrous silver calcium manganese oxide Aurora Mine, Hamilton, Treasure Hill District, Nevada 2354.jpg
General and classification
chemical formula (Mn 2+ , Ag, Ca) Mn 3 4+ O 7 · 3H 2 O
Mineral class
(and possibly department) 		Oxides and hydroxides
System no. to Strunz
and to Dana 		4.FL.20 ( 8th edition : IV / F.11)
08/07/02/02
Crystallographic Data
Crystal system trigonal
Crystal class ; symbol trigonal-rhombohedral; 3
Space group R 3 (No. 146) or R 3 (No. 148)Template: room group / 146Template: room group / 148
Lattice parameters a  = 7.51  Å ; c  = 20.73 Å
Formula units Z  = 6
Physical Properties
Mohs hardness 2 to 3
Density (g / cm 3 ) calculated: 3.81
Cleavage Please complete!
colour grey black
Line color brown
transparency opaque; transparent at very thin corners
shine Metallic luster

Aurorite is a rarely occurring mineral from the mineral class of " oxides and hydroxides ". It crystallizes in the trigonal crystal system with the chemical composition (Mn 2+ , Ag, Ca) Mn 3 4+ O 7 · 3H 2 O and thus represents the manganese analogue of the zinc-manganese oxide chalcophanite . This is also optically very similar looking mineral can only be distinguished by a chemical analysis.

Aurorite only develops microscopic crystals up to about 8 μm in flaky, tabular and granular mineral aggregates of black-brown color and metallic luster with brown streak color . The mineral is usually opaque, but in very thin layers it is light brown translucent.

Etymology and history

Aurorite was first discovered in 1967 in the "North Aurora Mine" at Summit on Treasure Hill in White Pine County (Nevada, USA) and described by Arthur S. Radtke, Charles M. Taylor and DF Hewett, who named the mineral after its type of locality .

classification

In the meanwhile outdated, but still in use 8th edition of the mineral systematics according to Strunz , the aurorite belonged to the mineral class of "oxides and hydroxides" and there to the department of "hydroxides and oxidic hydrates", where together with birnessite , chalcophanite, cianciulliite , ernienickelite and Jianshuiit formed a separate 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 the aurorite to the class of oxides, more precisely to the "oxides (hydroxides, V [5,6] vanadates, arsenides, antimonides , Bismuthide, Suldide, Selenide, Telluride, Jodide) "and there in the section" Hydroxide (without V or U) ". However, this section is further subdivided according to the presence of crystal water and / or hydroxyl groups as well as the type of link in the crystal structure, so that the mineral according to its composition and structure in the sub-section “Hydroxides with H 2 O ± (OH); Layers of edge-linked octahedra ”can be found where it forms the unnamed group 4.FL.20 together with chalcophanite, ernienickelite and jianshuiit .

The systematics of minerals according to Dana , which is common in the English-speaking world , assigns the aurorite to the class of "oxides and hydroxides", but there in the department of "multiple oxides". Here he is a member of the "Chalcophanite Group" with the system no. 07.08.02 with the other members Chalcophanite, Jianshuiit and Ernienickelite within the subdivision of " Multiple Oxides with Different Formulas ".

Crystal structure

Aurorite crystallizes trigonal in the space group R 3 (space group No. 146) or R 3 (No. 148) with the lattice parameters a  = 7.51  Å and c  = 20.73 Å as well as 6 formula units per unit cell . Template: room group / 146Template: room group / 148

Education and Locations

Aurorite forms as small vein fillings in microcracks of manganese-containing calcite and the following other accompanying minerals : chlorargyrite , cryptomelan , pyrolusite , solid silver , silver-containing todorokite and quartz .

So far (as of 2010) Aurorite has been found at around 20 sites worldwide. In the United States, the mineral occurred in addition to its type locality "North Aurora Mine" (Treasure Hill) in Nevada on Yucca Mountain and in the "Potosi Pit" in the Comstock Lode mine and at several sites in Arizona and Sterling Hill in New Jersey . Other sites are Kapunda in South Australia , Aghios Konstantinos in the Greek municipality of Lavrio , Shimoda in Japan and Argent in the South African province of Gauteng .

See also

literature

  • Aurorite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 69 kB ; accessed on January 24, 2018]).

Web links

Commons : Aurorite  - collection of images, videos and audio files

Individual evidence

  1. ^ A b c Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p.  244 .
  2. ↑ a b Aurorite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 69  kB ; accessed on January 24, 2018]).
  3. ^ A b Carl Hintze : Handbuch der Mineralogie , Walter de Gruyter & Co., Berlin, 1974 ISBN 3-11005850-2 , pp. 186–187 ( available online under Google book search )
  4. ↑ Wagnerul.de (Mineralogical part Lavrion) - Aurorit
  5. ^ AS Radtke, CM Taylor, DF Hewett: Aurorite, argentian todorokite, and hydrous silver-bearing lead manganese oxide. In: Economic Geology. 62, 1967, pp. 186-206, doi : 10.2113 / gsecongeo.62.2.186 .
  6. ↑ Find location list for aurorite at the Mineralienatlas and at Mindat (English)