Xocomecatlite
| Xocomecatlite | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 1974-048 |
| chemical formula | Cu 3 [(OH) 4 | Te 6+ O 4 ] |
|
Mineral class (and possibly department) |
Sulphates, Selenates, Tellurates, Chromates, Molybdates and Wolframates |
|
System no. to Strunz and to Dana |
7.BB.50 ( 8th edition : IV / K.15) 01.33.02.01 |
| Crystallographic Data | |
| Crystal system | orthorhombic |
| Crystal class ; symbol | not defined |
| Lattice parameters | a = 12.14 Å ; b = 14.32 Å; c = 11.66 Å |
| Formula units | Z = 12 |
| Physical Properties | |
| Mohs hardness | 4th |
| Density (g / cm 3 ) | measured: 4.65 (1); calculated: 4.42 |
| Cleavage | not defined |
| Break ; Tenacity | brittle |
| colour | emerald green |
| Line color | light green |
| transparency | translucent |
| shine | not defined |
| Crystal optics | |
| Refractive indices |
n α = 1.775 n β = 1.900 n γ = 1.920 |
| Birefringence | δ = 0.145 |
| Optical character | biaxial negative |
| Axis angle | 2V = 41 ° (measured); 40 ° (calculated) |
Xocomecatlite is a very rarely occurring mineral from the mineral class of "sulfates (including selenates, tellurates, chromates, molybdates and tungstates)" (formerly oxides and hydroxides, see classification ). It crystallizes in the orthorhombic crystal system with the chemical composition Cu 3 [(OH) 4 | Te 6+ O 4 ] and is therefore chemically seen a copper - tellurate with additional hydroxide .
Xocomecatlite develops needle-like crystals , which are usually arranged in transparent, radial to spherical mineral aggregates with a diameter of about 0.15 millimeters and an emerald green color.
Etymology and history
Xocomecatlite was first discovered together with tlalocite in the "Mina la Bambollita" ( Oriental Mine ) near Moctezuma in the Mexican state of Sonora and described in 1975 by SA Williams. He named the mineral based on its mostly greenish, spherical shape, which for him resembled green grapes , after the Nahua word (Mexican natives) xocomecatl (= grape). The mineral name should therefore be pronounced zho-ko-mecatl-ait after Williams .
Type material of the mineral is kept in the Muséum national d'histoire naturelle in Paris (France) and the National Museum of Natural History in Washington, DC (USA, catalog no. 135059).
classification
In the outdated, but partly still in use, 8th edition of the mineral classification according to Strunz , the xocomecatlite belonged to the mineral class of "oxides and hydroxides" and there to the department of "sulphites, selenites, tellurites", where it together with Cuzticit , Frankhawthorneit , Jensenit , Khinit , Kuranakhit , Leisingit , Mcalpineit , Montanit , Parakhinit , Utahit and Yafsoanit the group " Tellurates with [Te 6+ O 6 ] 6− -groups and related structures" with the system no. IV / K.15 .
The 9th edition of Strunz's mineral systematics, valid since 2001 and used by the International Mineralogical Association (IMA), assigns the xocomecatlite to the class of "sulfates (including selenates, tellurates, chromates, molybdates and tungstates)" and there in the department the “sulfates (selenates etc.) with additional anions, without H 2 O”. However, this is further subdivided according to the relative size of the cations involved , so that the mineral can be found according to its composition in the sub-section “With medium-sized cations”, where it is the only member of the unnamed group 7.BB.50 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking area , assigns the xocomecatlite to the class of "sulfates, chromates and molybdates (including selenates, tellurates, selenites, tellurites, sulphites)" and there in the category of "selenates and tellurates". Here he is the only member of the unnamed group 33.01.02 within the subdivision “ 33.01 Selenates and Tellurates with A + (B 2+ ) m XO 4 Z q ”.
Crystal structure
Xocomecatlite crystallizes orthorhombically in a previously unspecified space group with the lattice parameters a = 12.14 Å ; b = 14.32 Å and c = 11.66 Å as well as 12 formula units per unit cell .
Education and Locations
Xocomecatlit forms as rare secondary mineral in the oxidation zone of hydrothermally formed Gold - tellurium - deposits . As Begleitminerale occur among other Dugganit , goethite , Hinsdalite , Jensenit , Leisingit , Mcalpineit , Parakhinit and Svanbergit on.
So far (as of 2014) Xocomecatlite could only be detected in a few samples from less than 10 locations. Its type locality "Mina la Bambollita" near Moctezuma is the only known site in Mexico so far.
Other previously known sites are the "Old Guard Mine" (Royal Guard Mine) and "Emerald Mine" near Tombstone in Cochise County of Arizona, the "Bird Nest Drift" on Otto Mountain near Baker in California and the "Centennial Eureka Mine" ( Blue Rock) in the Tintic District ( Juab County ) and the "Trixie Mine" in the East Tintic District ( Utah County ) in Utah in the United States.
See also
literature
- SA Williams: Xocomecatlite, Cu 3 TeO 4 (OH) 4 , and tlalocite, Cu 10 Zn 6 (TeO 3 ) (TeO 4 ) 2 Cl (OH) 25 · 27H 2 O, two new minerals from Moctezuma, Sonora, Mexico. In: Mineralogical Magazine. Volume 40, 1975, pp. 221-226 ( PDF 295.9 kB ).
- Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p. 808 .
Web links
- Mineral Atlas: Xocomecatlite (Wiki)
- Webmineral - Xocomecatlite
- Database-of-Raman-spectroscopy - Xocomecatlite
Individual evidence
- ↑ a b c d 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. 371 .
- ^ Xocomecatlite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( PDF 67.1 kB ).
- ↑ a b c Mindat - Xocomecatlite
- ↑ SA Williams: Xocomecatlite, Cu 3 TeO 4 (OH) 4 , and tlalocite, Cu 10 Zn 6 (TeO 3 ) (TeO 4 ) 2 Cl (OH) 25 · 27H 2 O, two new minerals from Moctezuma, Sonora, Mexico . In: Mineralogical Magazine. Volume 40, 1975, pp. 221-226 ( PDF 295.9 kB ).
- ↑ Find location list for Xocomecatlite in the Mineralienatlas and Mindat