Dugganit

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Dugganit
Dugganite - Tombstone, Cochise County, Arizona.jpg
Greenish dugganite from the type locality Tombstone, Arizona, USA (image width 1.8 mm)
General and classification
other names

IMA1978-034

chemical formula
  • Pb 3 Zn 3 (TeO 6 ) (AsO 4 ) 2
  • Pb 3 [8] Te [6] Zn 3 [4] [O 6 | (AsO 4 ) 2 ]
Mineral class
(and possibly department) 		Phosphates, Arsenates and Vanadates (formerly oxides and hydroxides, including related compounds)
System no. to Strunz
and to Dana 		8th BL.20 ( 8th edition : IV / K.16)
03.33.05.03
Crystallographic Data
Crystal system trigonal
Crystal class ; symbol trigonal trapezoidal; 32
Room group (no.) P 321 (No. 150)
Lattice parameters a  = 8.460 (2)  Å ; c  = 5.206 (2) Å
Formula units Z  = 1
Frequent crystal faces {0001}, {11 2 0}, {11 2 1}
Physical Properties
Mohs hardness 3
Density (g / cm 3 ) measured: 6.33 (15); calculated: 6.33
Cleavage indistinct after {11 2 0}
Break ; Tenacity brittle
colour colorless, green, yellow-green
Line color White
transparency transparent to translucent
shine Diamond luster
Crystal optics
Refractive indices n ω  = 1.977
n ε  = 1.967
Birefringence δ = 0.010
Optical character uniaxial negative

Dugganite is a rarely occurring mineral from the mineral class of "phosphates, arsenates and vanadates". It crystallizes in the trigonal crystal system with the chemical composition Pb 3 Zn 3 (TeO 6 ) (AsO 4 ) 2 ( molecular formula : Pb 3 Zn 3 Te 6+ As 2 O 14 ) and is thus chemically seen a lead - zinc - tellurate - arsenate .

Dugganit only develops small, short prismatic crystals up to about 0.3 millimeters in size with slightly curved prismatic surfaces, which gives them a " barrel-shaped " appearance, similar to some varieties of pyromorphite ( Emser barrel ) and mimetesite ( kampylite ).

In its pure form, Dugganit is colorless and transparent. However, due to multiple refraction due to lattice construction defects or polycrystalline formation, it can also appear white and, due to foreign admixtures, take on a green to yellow-green color, the transparency decreasing accordingly.


Etymology and history

Dugganit was named after the American chemist for analytical chemistry Marjorie Duggan (* 1927), who was the first to detect tellurium in the Te 6+ oxidation state in naturally occurring compounds and developed techniques for the microanalysis of Te 4+ and Te 6+ .

Was first discovered Dugganit with Khinit and Parakhinit in an emerald mine ( Emerald Mine ) near the former "Boomtown" Tombstone in Cochise County of the US state of Arizona . The first description of the minerals was published in 1978 by SA Williams.

Type material of the mineral is in the Natural History Museum in London, England (Catalog No. 1980,544); at Harvard University in Cambridge, Massachusetts, (catalog number 119093) and in the National Museum of Natural History in Washington, DC, USA (catalog number 162207).

classification

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

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), assigns the Dugganit to the class of "phosphates, arsenates and vanadates" and there to the department of "phosphates etc. with additional anions ; without H 2 O “. However, this is further subdivided according to the relative size of the cations involved and the molar ratio of the additional anions to the phosphate, arsenate or vanadate complex (RO 4 ), so that the mineral can be classified in the sub-section “With medium-sized and large cations; (OH etc.): RO 4  = 3: 1 ”can be found where the“ Dugganitgruppe ”with the system no. 8.BL.20 and the other members Cheremnykhit, Joëlbruggerit and Kuksit.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the dugganite to the class of "sulfates, chromates and molybdates (including selenates, tellurates, selenites, tellurites and sulfites)" and there in the category of "selenates and tellurates". Here he is together with Cheremnykhit, Joëlbruggerit and Kuksit in the group of Pb, Zn tellurates with the system no. 33.03.05 to be found in the subsection “ Selenates and Tellurates with other anion groups ”.

Education and Locations

Dugganite is secondary to the weathering of khinite and parakhinite in the oxidation zone of tellurium-containing deposits . In addition to the reactants khinite and parakhinite, bromine argyite , cerussite , chlorine argyite and emmonsite can occur as accompanying minerals .

As a rare mineral formation, Dugganit could only be detected at a few sites, with around 15 sites known so far (as of 2014). In addition to its type locality "Emerald Mine" and the nearby mines "Empire Mine", "Joe Mine" and "Old Guard Mine" at Tombstone and the "Reef Mine" in Carr Canyon near Hartford in Cochise County of Arizona, the mineral was able to move to the United States States can still be found in the "Blue Bell Mine" near Baker in California, in the "Black Pine Mine" in Black Pine Ridge near Philipsburg in Granite County of Montana and in some mines in the Tintic Mountains between Utah and Juab Counties in Utah .

Other previously known localities are the "Kawazu Mine" at Rendaiji in Shizuoka Prefecture on the Japanese island of Honshu, the "Bambollita Mine" ( Oriental Mine ) in Moctezuma (Sonora) in Mexico and the Delbe- ore body in the gold deposit Kuranakh in Aldanhochland the Russian Republic Sakha ( Yakutia , see also Polyus Gold ).

Crystal structure

Dugganite crystallizes trigonally in the space group P 321 (space group no. 150) with the lattice parameters a  = 8.460 (2)  Å and c  = 5.206 (2) Å as well as one formula unit per unit cell .

See also

literature

  • SA Williams: Khinite, parakhinite, and dugganite, three new tellurates from Tombstone, Arizona. In: American Mineralogist. Volume 63 (1978), pp. 1016-1019 ( PDF 427.3 kB )
  • John Leslie Jambor , David A. Vanko: New mineral names. In: American Mineralogist. Volume 76 (1991), pp. 1434-1440 ( PDF 896 kB )

Web links

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

Individual evidence

  1. ↑ a b IMA / CNMNC List of Mineral Names; March 2014 (PDF 1.5 MB)
  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.  464 .
  3. ↑ a b c d Anita E. Lam, Lee A. Groat, T. Scott Ercit: The crystal structure of dugganite, Pb 3 Zn 3 Te 6+ As 2 O 14 . In: The Canadian Mineralogist. Volume 36 (1998), pp. 823-830 ( PDF 548.2 kB )
  4. ↑ a b c d e Dugganite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 60.8 kB )
  5. ↑ a b Mindat - Dugganite
  6. ↑ SA Williams: Khinite, parakhinite, and dugganite, three new tellurates from Tombstone, Arizona. In: American Mineralogist. Volume 63 (1978), p. 1019 ( PDF 427.3 kB ; p. 4)
  7. ↑ SA Williams: Khinite, parakhinite, and dugganite, three new tellurates from Tombstone, Arizona. In: American Mineralogist. Volume 63 (1978), pp. 1016-1019 ( PDF 427.3 kB )
  8. ↑ Mindat - Number of localities for Dugganit
  9. ↑ Find location list for Dugganit at the Mineralienatlas and at Mindat