Murdochit
| Murdochit | |
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| General and classification | |
| chemical formula |
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Mineral class (and possibly department) |
Please complete |
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System no. to Strunz and to Dana |
3.DB.45 ( 8th edition : IV / A.04) 06/04/05/01 |
| Crystallographic Data | |
| Crystal system | cubic |
| Crystal class ; symbol | cubic hexakisoctahedral; 4 / m 3 2 / m |
| Room group (no.) | Fm 3 m (No. 225) |
| Lattice parameters | a = 9.22 Å |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | 4th |
| Density (g / cm 3 ) | measured: 5.9 to 6.7; calculated: 6.06 |
| Cleavage | after {111} |
| colour | black, in incident light gray with a yellowish-brown tinge |
| Line color | black |
| transparency | opaque |
| shine | Diamond luster |
Murdochite is a rarely occurring mineral from the mineral class of " halides " (formerly " oxides and hydroxides ", see classification ). The originally determined chemical formula Cu 6 PbO 8 was corrected on the basis of more recent analyzes according to Cu 12 Pb 2 O 15 Cl 2 or more precisely according to PbCu 6 O 8 − x (Cl, Br) 2x (x ≤ 0.5). The elements chlorine and bromine indicated in round brackets can represent each other in the formula ( substitution , diadochie), but are always in the same proportion to the other components of the mineral.
Murdochite crystallizes in the cubic crystal system , but develops only small, octahedral or cuboctahedral crystals up to a maximum of two millimeters in size. These often cover other minerals as crusty coatings or "crystal turf" such as B. malachite , hemimorphite or limonite . The surfaces of the opaque and black crystals have a diamond-like sheen . In incident light, Murdochite can also appear gray with a tinge of yellowish brown. However, he always leaves a black line on the whiteboard .
Etymology and history
Murdochite was first discovered in the "Mammoth-Saint Anthony Mine" (also Mammoth-St Anthony Mine , Mammoth Mine or St. Anthony Mine ) near St. Anthony near the former town of Tiger in Pinal County of Arizona (USA). The mineral was described in 1953 by Joseph J. Fahey, who named it after the American mineralogist Joseph Murdoch (1890–1973).
classification
In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , Murdochite still belonged to the mineral class of "oxides and hydroxides" and there to the department of "oxides with the molar ratio of metal: oxygen = 2: 1 and 1: 1", where together with bunsenite , calcium oxide , manganosite , monteponite , periclase and wüstite the "periclase group" with the system no. IV / A.04 .
The 9th edition of Strunz's mineral systematics, which has been valid since 2001 and is used by the International Mineralogical Association (IMA), assigns Murdochite to the class of "halides" and there to the department of "oxyhalides, hydroxyhalides and related double halides" . This department is also further divided according to prevailing in the connection metals, so that the mineral according to its composition in the subsection "With Pb, Cu, etc." is to find where it is the only member of the unnamed group 3.DB.45 forms .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Murdochite, like the outdated Strunz system, to the class of "oxides and hydroxides" and there in the department of "oxides". Here he is to be found as the only member in the unnamed group 04.06.05 within the subdivision of the " Simple unclassified oxides ".
Education and Locations
Murdochite is found in oxidized lead - copper - deposits . The accompanying minerals include Boleit , Creaseyite , Chrysocolla , Descloizit , Diaboleit , Dioptas , Embolite , Fluorite , Hemimorphite , Iranite , Limonite , Malachite , Plattnerite , Quartz , Willemite and Wulfenite .
As a rare mineral formation, Murdochite has so far only been proven at a few sites, with around 30 sites (as of 2012) being known. In addition to its type locality “Mammoth-Saint Anthony Mine” near St. Anthony and the “Silver Reef Mine” in the Silver Reef Mountains, also located in Pina County, the mineral was also found in several mines near Bisbee in the United States , in the “79th Mine "At Chilito (Hayden, Gila County), the" Eagle Eye Mine "(La Paz County), the" Evening Star Mine "and the" Tonopah-Belmont Mine "at Tonopah (Maricopa County) and the" Silver Hill Mine "( Pima County) in Arizona as well as several other mines in California, Nevada, and New Mexico.
Furthermore, Murdochit was still in the "Whim Creek Copper Mine" near Whim Creek in the Pilbara region of Western Australia, the "Dos Adriana Mine" and the "Los Azules Mine" near Zapallar in the Chilean Región de Atacama , the "Agia Varvara Mines ”(St Barbara Mines) at Cape Sounion in Greece, the“ Chah Khouni Mine ”near Anarak in the Iranian province of Isfahan as well as in the“ San Antonio Mine ”near Santa Eulalia ( Chihuahua ) and the“ Ojuela Mine ”near Mapimí (Durango ) found in Mexico.
Crystal structure
Murdochite crystallizes cubically in the space group Fm 3 m (space group no. 225) with the lattice parameter a = 9.22 Å and 4 formula units per unit cell .
See also
literature
- CL Christ, Joan R. Clark (1955): The crystal structure of murdochite , in: American Mineralogist , Volume 40, pp. 907-916 ( PDF 540.8 kB )
Web links
- Mineral Atlas: Murdochite (Wiki)
Individual evidence
- ↑ a b IMA / CNMNC List of Mineral Names - Murdochite (PDF 1.8 MB; p. 196)
- ↑ a b c d John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols: Murdochite , in: Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 68.6 kB )
- ↑ Webmineral - Murdochite
- ^ A b c Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 175 .
- ↑ Joseph J. Fahey (1955): Murdochite, a new copper lead oxide mineral , in: American Mineralogist , Volume 40, pp. 905–906 ( PDF 113 kB )
- ↑ Mindat - Number of localities for Murdochit
- ↑ Mindat - Murdochite