Murdochite
- Cu12Pb2O15Cl2 or more precisely
- PbCu6O8 -x ( Cl, Br) 2 x (x ≤ 0.5 )
Murdochit is a rarely occurring mineral from the mineral class of " halides " (formerly " oxides and hydroxides ", see Classification ). The originally identified chemical formula Cu6PbO8 was corrected 2x (x ≤ 0.5 ) due to recent analyzes by Cu12Pb2O15Cl2 or more precisely to PbCu6O8 -x (Cl, Br). The values given in the parentheses elements chlorine and bromine in the formula each represent each other (substitution, Diadochie ), but are always in the same proportions to the other components of the mineral.
Murdochit crystallizes in the cubic crystal system, but developed only small, octahedral or cuboctahedral crystals up to two millimeters in size. This often put on as crusty coatings or " crystal lawn " other minerals such as Malachite, hemimorphite or limonite. The surfaces of the opaque and black crystals have a diamond-like luster. In reflected light Murdochit can also appear gray with a tinge of yellowish brown. However, on the dash board, he always leaves a black line.
Etymology and history
Was first discovered Murdochit in the " Mammoth -Saint Anthony Mine" (also Mammoth -St Anthony Mine, Mammoth Mine or St. Anthony Mine) at St. Anthony near the former place in Pinal County Tigers of Arizona (USA). This has been described mineral in 1953 by Joseph J. Fahey, who named it after the American mineralogist Joseph Murdoch ( 1890-1973 ).
Classification
In the now outdated but still in use 8th edition of the mineral classification by Strunz the Murdochit still belonged to the mineral class of " oxides and hydroxides " and then to the Department of " oxides with the molar ratio of metal: oxygen = 2: 1 and 1: 1" where he collaborated with bunsenite, calcium oxide, Manganosit, Monteponit, periclase and wüstite the " periclase - group " with the system no. IV/A.04 formed.
The 9th edition valid since 2001 and of the International Mineralogical Association (IMA ) used the Strunz'schen Mineral classification assigns the Murdochit other hand, in the class of " halides " and there in the department of " oxyhalides, hydroxyhalides and related double halides " a. This department is also further divided according to the conditions prevailing in the interconnect metals, so that the mineral "With Pb, Cu, etc. ," according to its composition in the sub-division is to find where it is the only member of the unnamed group 3.DB.45 forms.
The mostly commonly used in English-speaking classification of minerals according to Dana assigns a the Murdochit as the outdated Strunzsche systematics in the class of " oxides and hydroxides " and there in the department of " oxides ". Here he can be found as the only member of the unnamed group 04:06:05 within the sub-division of " not classified Simple oxides ".
Education and Locations
Murdochit found in oxidized lead - copper deposits. Accompanying minerals occur among others Boleite, Creaseyite, chrysocolla, Descloizit, Diaboleit, Dioptase, Embolit, fluorite, hemimorphite Iranit, limonite, malachite, Plattnerit, quartz, willemite and Wulfenite.
A rare mineral formation Murdochit has so far demonstrated only in a few localities, of which approximately 30 localities (as of 2012) are considered to be known. Apart from its type locality " Mammoth -Saint Anthony Mine" at St. Anthony and also located in the County Pina " Silver Reef Mine" in the Silver Reef Mountains, the mineral in the United States occurred yet in several mines in Bisbee, 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 in some other mines in California, Nevada and New Mexico on.
Furthermore Murdochit was still in the " Whim Creek Copper Mine" at Whim Creek in the Pilbara region of Western Australia, the " Dos Adriana Mine" and the " Los Azules Mine" at Zapallar in the Chilean Atacama region, the " Agia Varvara Mines " (St Barbara Mines ) at Cape Sounion in Greece, the " Chah Khouni Mine " at Anarak in the Iranian province of Isfahan and in the " San Antonio Mine " at Santa Eulalia (Chihuahua ) and the " Ojuela Mine " at Mapimí (Durango ) found in Mexico.
Crystal structure
Murdochit crystallizes in cubic space group Fm3m ( Raumgruppen-Nr. 225 ) with the lattice parameters a = 9.22 Å and four formula units per unit cell.