Tlalocite

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Tlalocite
Tlalocite-130808.jpg
Tlalocite in capri-blue spherical aggregates on azurite from the Bambollita mine near Moctezuma, Sonora, Mexico (field of view: 3 mm)
General and classification
other names

IMA 1974-047

chemical formula
  • Cu 10 Zn 6 TeO 3 (TeO 4 ) 2 Cl (OH) 25 · 27H 2 O
  • Cu 10 Zn 6 [(OH) 25 | Cl | TeO 3 | (TeO 4 ) 2 ] · 27H 2 O
  • (Cu, Zn) 16 (Te 4+ O 3 ) (Te 6+ O 4 ) 2 Cl (OH) 25 · 27H 2 O
Mineral class
(and possibly department) 		Sulphates (selenates etc.) with other anions, with H 2 O
System no. to Strunz
and to Dana 		7.DE.20 ( 8th edition : IV / K.16)
06.22.07.01
Similar minerals Quetzalcoatlite
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol unknown
Space group unknown
Lattice parameters a  = 16.780  Å ; b  = 19.985 Å; c  = 12.069 Å
Formula units Z  = 4
Physical Properties
Mohs hardness 1
Density (g / cm 3 ) 4.55 (measured); 4.58 (calculated)
Cleavage not given
Break ; Tenacity not given; cuttable, rubbery
colour capri blue
Line color all pale blue
transparency translucent
shine not given
Crystal optics
Refractive indices n α  = 1.758
n β  = 1.796
n γ  = 1.810
Birefringence δ = 0.052
Optical character biaxial negative
Axis angle 2V = 64 ° (measured), 2V = 61 ° (calculated)
Pleochroism weakly from X = yellowish green to Y = Z = bluish green
Other properties
Chemical behavior Dissolution in ENT 3

Tlalocite (pronounced in English "tla-lawk-ait", in Spanish "tlalocquita") is a very rarely occurring mineral from the mineral class of " sulfates " (and relatives, see classification ). It crystallizes in the orthorhombic crystal system with the idealized composition Cu 10 Zn 6 TeO 3 (TeO 4 ) 2 Cl (OH) 25 27H 2 O, so chemically speaking it is a water-containing copper - zinc - tellurite - tellurate with additional hydroxide ions and chloride ions .

Tlalocite forms curved bands of sub-parallel, latte crystals up to 10 µm in size, which come together to form spherical or spherulitic aggregates . It was found in partially oxidized areas of a tellurium- containing polymetallic hydrothermal sulphide vein in the "Mina la Bambollita" (Mina la Oriental), Sonora , Mexico , 12 km south of Moctezuma, accompanied by tenorite, azurite, malachite and an amorphous pea-green copper Te-Minerals.

Etymology and history

Tlaloc was the rain god of the Aztecs and Toltecs. The mineral tlalocite was named after him because of its extremely high content of crystal water.

The American geologist and mineralogist Sid Williams from the Phelps Dodge Corporation in Douglas, Arizona / USA, found the beginning in the ore stockpile near Nacozari, Sonora, not far from the “Mina la Bambollita”, which already provided the material for the first description of the Quetzalcoatlite In the 1970s, another unassigned mineral was "cut through". Corresponding investigations led to the determination of the presence of a new mineral, which was recognized by the International Mineralogical Association (IMA) in 1974 and described in 1975 by Sidney Arthur Williams (1933-2006) in the English scientific journal "Mineralogical Magazine" as Tlalocite. The mineral was named after Tlaloc , who was one of the most important gods of the Aztec circle of gods and was generally associated with all weather phenomena by the Aztecs , but is often referred to as the "rain god".

Type material of the mineral is in the collection of Harvard University , Cambridge , Massachusetts (Collection no. 119091), in the collection of the Smithsonian Institution belonging to National Museum of Natural History , Washington, DC (Collection no. 135057, 144519) and in the collections of the École nationale supérieure des mines ( Mines ParisTech ), the Muséum national d'histoire naturelle , both in Paris , France , and the Natural History Museum , London .

classification

In the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the tlalocite belonged to the mineral class of "oxides and hydroxides (including V [5,6] vanadates, arsenites, sulfites, selenites, tellurites and iodates)" Department of "Sulphites, Selenites, Tellurites", where he formed the unnamed group IV / K.16 together with Cheremnykhit , Dugganit and Kuksit .

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the IMA, assigns tlalocite to the class of "sulfates (selenates, tellurates, chromates, molybdates and tungstates)" and then to the department of "sulfates (selenates, etc.)" ) with additional anions , with H 2 O “. However, this division is further subdivided according to the relative size of the cations involved and the crystal structure. Since the crystal structure of tlalocite has not yet been able to be determined more precisely, it is listed in the subsection “With only medium-sized cations; unclassified ”, where he is the only member of the unnamed group 7.DE.20 .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns tlalocite to the class of “sulfates, chromates and molybdates” and there to the category of “ selenates and tellurates ”. Here he is the only member in the unnamed group with the system no. 33.03.02 to be found in the subsection “ Selenates and Tellurates with other anion groups ”.

Chemism

Various partial analyzes of the tlalocite yielded contents of 15.0% TeO 3 , 6.1% TeO 2 , 31.0% CuO, 19.3% ZnO, 1.3% Cl and 27.7% H 2 O, from which the measured composition Cu 9.92 Zn 6.03 (Te 4+ O 3 ) 0.97 (Te 6+ O 4 ) 2.17 Cl 0.93 (OH) 24.69 · 26.78H 2 O gives. This composition was to Cu 10 Zn 6 TeO 3 (TeO 4 ) 2 Cl (OH) 25 · 27H 2 idealized O, which contents of 13.8% TeO 3 , 6.3% of TeO 2 , 31.4% CuO, 19 , 3% ZnO, 1.4% Cl and 28.1% H 2 O. The notation on the cation side with (Cu, Zn) 16 represents a disordered version, whereas the notation Cu 10 Zn 6 represents an ordered version of the formula. The level of the water content in the Tlalocit is doubted.

Crystal structure

Tlalocite crystallizes orthorhombically with the lattice parameters a  = 16.780  Å ; b  = 19.985 Å and c  = 12.069 Å as well as four formula units per unit cell .

The crystal structure of the Tlalocite has not yet been clarified (as of 2016). It is assumed that the structure of tlalocite - as well as of Utahit and Eurekadumpit - is based on Cu and Zn polyhedra oriented perpendicular to [001]. However, the character and arrangement of the anions and H 2 O molecules are different in every mineral. Based on the stable stoichiometric relationship between copper and zinc (Cu: Zn = 5: 3), the structural pattern in all of these minerals is similar and the arrangement of the Cu and Zn atoms is ordered, as in the tellurite mineral quetzalcoatlite and some natural arsenates and phosphates has been found.

properties

morphology

Tlalocite forms latte to leafy crystals up to 10 µm in size, arranged sub-parallel , which come together to form spherical, spherulitic or even grape-like aggregates .

physical and chemical properties

Tlalocite crystals are capri blue, but their line color is always white. The surfaces of the semi-transparent (translucent) aggregates show a velvety sheen . Tlalocite has medium to high light refraction and medium double refraction (δ = 0.025). In transmitted light, tlalocite is pale green and resembles rosasite. It shows a weak pleochroism from X = yellowish green to Y = Z = bluish green.

There is no information on the cleavage of the tlalocite or its breakage (mineral) . Tlalocit is rubbery and cuttable. It has a Mohs hardness of 1 and is therefore one of the soft minerals that, like the reference mineral talc , can be scraped off with a fingernail. The measured density for tlalocite is 4.55 g / cm³, the calculated density is 4.58 g / cm³.

Education and Locations

Tlalocite formed under extremely oxidizing conditions in areas of a tellurium -containing polymetallic hydrothermal sulphide vein. It can be found in or near the richest ore batches - but always only on the surfaces of those cracks and fractures in the ore that were subject to the most intensive oxidation. It was also found in cavities created by the dissolution of former sulphidic ore minerals. Accompanying minerals are tenorite , azurite , malachite , hessite and an amorphous, pea-green Cu-Te mineral.

As a very rare mineral formation, Tlalocite could so far (as of 2016) only be described by its type locality. The type locality for the mineral is "Mina la Bambollita" (Mina la Oriental), Municipio Moctezuma , Sonora , Mexico , 12 km south of Moctezuma . Find places in Germany , Austria and Switzerland are therefore not known.

A mineral originally identified as tlalocite from the "Blue Bell Mine" near Baker , Soda Lake Mts, San Bernardino County , California , USA , has been shown to be quetzalcoatlite.

use

Due to its rarity, tlalocite is a sought-after mineral by mineral collectors, but otherwise of no practical importance.

See also

literature

  • Sidney Arthur 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 . tape 40 , 1975, pp. 221–226 ( rruff.info [PDF; 315 kB ]).
  • Paul Ramdohr , Hugo Strunz : Klockmann's textbook of mineralogy . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 837 (first edition: 1891).
  • 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. 427 .

Web links

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

Individual evidence

  1. ↑ a b c d e f g h i j k Sidney Arthur 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 . tape 40 , 1975, pp. 221–226 ( rruff.info [PDF; 315 kB ]).
  2. ^ 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.  406 .
  3. ↑ a b c d e f g h i j Tlalocite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF, 67 kB )
  4. ↑ Mindat - Tlalocit
  5. ↑ Michael Fleischer, Ray E. Wilcox, John J. Matzko: Microscopic determination of the non-opaque minerals (US Geological Survey Bulletin 1627) . 3. Edition. US Government Printing Office, Washington DC 1984, p. 292 .
  6. ↑ Catalog of Type Mineral Specimens - T. (PDF 87 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, accessed August 29, 2019 .
  7. ↑ a b c Igor V. Pekov, Nikita V. Chukanov, Aleksandr E. Zadov, Andrew C. Roberts, MC Jensen, NV Zubkova, Anthony J. Nikischer: Eurekadumpite, (Cu, Zn) 16 (TeO 3 ) 2 (AsO 4 ) 3 Cl (OH) 18 ⋅7 H 2 O, a new supergene mineral species . In: Geology of Ore Deposits . tape 53 , 2011, p. 575-582 , doi : 10.1134 / S1075701511070178 .
  8. ↑ a b Christian Rewitzer: Bambollita, Bambolla, San Miguel and Candelaria: Underground finds and type minerals . In: Lapis . 26 (Issue 1), 2007, pp. 24-40 + 58 .
  9. ↑ Mindat - Number of localities for Tlalocit
  10. ↑ Find location list for Tlalocite at the Mineralienatlas and at Mindat
  11. ^ Robert M. Housley: Recent discoveries of tlalocite, kuksite, and other rare minerals from the Blue Bell mine, San Bernardino County, California . In: San Bernardino County Museum Association Quarterly . tape 44 , 1997, pp. 9-12 .
  12. ^ Anthony R. Kampf, George R. Rossman, Robert M. Housley: Plumbophyllite, a new species from the Blue Bell claims near Baker, San Bernardino County, California . In: The American Mineralogist . tape 94 , 2009, p. 1198–1204 , doi : 10.2138 / am.2009.3156 .