Nausea

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Nausea
General and classification
other names

IMA 1979-029

chemical formula
  • PbFeGe [VI] (Ge [IV] 2 O 7 ) (OH) 2 • H 2 O
  • PbFe 2+ Ge 3 O 8
  • PbFe [Ge 3 O 8 ]
Mineral class
(and possibly department) 		Silicates and Germanates
System no. to Strunz
and to Dana 		9.JA.10 ( 8th edition : IV / C.08)
07.06.02.01
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group P 2 1 / m (No. 11)Template: room group / 11
Lattice parameters a  = 5.8279  Å ; b  = 13.6150 Å; c  = 6.3097 Å
β  = 127.314 °
Formula units Z  = 2
Physical Properties
Mohs hardness ≈ 4
Density (g / cm 3 ) 4.97 (calculated); 5.36 (calculated)
Cleavage indistinct after {101}
Break ; Tenacity not specified; not specified
colour colorless, white to pale greenish
Line color White
transparency translucent to translucent
shine Fat luster (semi-diamond luster)
Crystal optics
Refractive indices n α  = 1.885
n β  = 1.910
n γ  = 1.913
Birefringence δ = 0.028
Optical character biaxial negative
Axis angle 2V = ≈ 35 °
Other properties
Chemical behavior soluble in hot HCl

Bartelkeit is a very rare mineral from the mineral class of " silicates and germanates " (formerly oxides and hydroxides ). It crystallizes in the monoclinic crystal system with the chemical composition PbFeGe [VI] (Ge [IV] 2 O 7 ) (OH) 2 · H 2 O, and is thus chemically seen a crystal water-containing lead - iron -Germanat with additional hydroxide .

Bartelkeit forms idiomorphic , either tabular according to {10 1 } or acicular-elongated crystals according to [101] up to a maximum of 1 mm in length, which have grown together to form aggregates with a radial structure. The mineral was found - together with chalcosine , quartz and wulfenite - in corroded germanite - renierite - galena ore in the Tsumeb Mine , Namibia.

Etymology and history

The German hobby mineralogist Wolfgang Bartelke (* 1949), who noticed the mineral among other specimens from Tsumeb, is considered to be the discoverer of Bartelkeit . Corresponding investigations led to the determination of the presence of a new mineral, which was recognized in 1979 by the International Mineralogical Association (IMA) and published in 1981 by a German-American research team with Paul Keller , Heinz Hess and Pete J. Dunn in the science magazine "Chemie der Erde" was described as barbarism. The mineral was named after the finder Wolfgang Bartelke, an enthusiastic mineral collector, specialist in Tsumeb minerals and co-author of important works on the mineralogy of the Tsumeb Mine. The structure of barbarity could only be resolved more than 30 years after it was first described.

Type material of the mineral is located in the archive of the University of Stuttgart in the "Mineralogical Collection of Professor Keller" (register no. NM07, Cotyp) as well as in the National Museum of Natural History , Washington, DC (register no. 148302, belonging to the Smithsonian Institution ) Cotype).

classification

In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , bitterness belonged to the mineral class of " oxides and hydroxides " and there to the department of "oxides with the molar ratio metal: oxygen = 2: 3 (M 2 O 3 and related compounds) ", where he together with Batiferrit , Haggertyit , Hawthorneit , Hibonit , Lindqvistit , magnetoplumbite , Nežilovit , Otjisumeit , Plumboferrit , Yimengit and Zenzénit the" magnetoplumbite group "with the system number. IV / C.08 .

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 barbarity to the class of “silicates and Germanates” and there in the “Germanates” department. Here he can be found as the only member of the unnamed group 9.JA.10 within the previously unnamed subdivision "A".

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the barbarity to the class of "oxides and hydroxides" like the outdated Strunz'sche systematics, although there it is in the category of "multiple oxides". Here he can be found as the only member of the unnamed group 07.06.02 within the subdivision of " Multiple oxides with the formula A (B) 4 X 9 ".

Chemism

Mean values ​​from 18 microprobe analyzes of barbarity showed 34.1% PbO; 10.6% FeO; 46.2% GeO 2 ; 0.08% ZnO; 0.10% SiO 2 ; 2.8% As 2 O 5 ; 0.04% P 2 O 5 and 0.14% SO 3 . On the basis of 10 (O + Cl) atoms per formula unit and after adding 5.64% by weight of H 2 O, the empirical formula Pb 0.97 (Fe 2+ 0.94 Zn 0.01 ) Σ resulted = 0.95 VI Ge 1.00 IV (Ge 1.81 As 0.16 Si 0.01 S 0.01 ) Σ = 1.99 O 7 [(OH) 1.94 Cl 0.04 ] Σ = 1 , 98 · 1.02H 2 O idealized to PbFe [VI] Ge ( [IV] Ge 2 O 7 ) (OH) 2 · H 2 O.

Crystal structure

Bartelkeit crystallizes monoclinically in the space group P 2 1 / m (space group no. 11) with the lattice parameters a  = 5.8279  Å ; b  = 13.6150 Å; c  = 6.3097 Å and β = 127.314 ° as well as two formula units per unit cell . Template: room group / 11

The crystal structure of the Bartelkeits consists of individual chains of FeO 6 - and Ge1O 6 - octahedra with common edges which are arranged parallel to the c-axis [001] and tetrahedral Ge 2 O 7 - dimers are cross-linked. The lead atoms and the H 2 O groups fill large cavities in this network. The scheme of hydrogen bonds in Bartelkeit is similar to that in Lawsonite. Bartelkeit is the first mineral with [4] and [6] -fold coordinated germanium atoms .

Bar nausea is isotypic (isostructural) to the high pressure P 2 1 / m phase of Lawsonite, which is only stable above 8.6 GPa . Template: room group / 11

properties

morphology

Nausea is mostly found in idiomorphic crystals with a maximum size of 1.0 mm × 0.3 mm × 0.2 mm, which are formed differently on the two finds known at the time the type was published. The flat shapes {10 1 }, {101}, {111} and possibly also {010} belong to the crystal costume of barbarity . At the first discovery the crystals have a tabular habit according to {10 1 } and are only slightly elongated according to [101]. The {111} faces of these crystals also have a characteristic serration. In the second finding, on the other hand, the crystals are more or less finely needle-like according to [101] and have grown together to form radial aggregates.

physical and chemical properties

Nausea crystals are colorless or white to pale green in color, but their line color is always white. The surfaces of the crystals, which are water-clear to translucent, depending on their color, show a distinct semi-diamond-like or greasy sheen .

The crystals of Bartelkeit show an indistinct cleavage according to {101}. The mineral has a Mohs hardness of ≈ 4 and is therefore one of the medium-hard minerals that, like the reference mineral fluorite, can be easily scratched with a pocket knife. Measured values ​​for the density of barness do not exist, the calculated density for the mineral is 5.36 g / cm³.

Bart nausea is soluble in hot hydrochloric acid HCl.

Education and Locations

Dizziness arises as a typical secondary formation in the heavily corroded lead ore of a complex Cu-Pb-Zn deposit in carbonate rocks. Lead, iron and germanium originate from the decomposition of primary Germanium - ores and sulfidic ore minerals as Germanit , Renierit , tennantite and galena . Accompanying minerals include germanite, renierite, tennantite and galena as well as chalcosin, quartz and wulfenite.

So far (as of 2018), barbarity could only be described from one source as a very rare mineral formation. Its type locality is the world-famous Cu-Pb-Zn-Ag-Ge-Cd deposit of the "Tsumeb Mine" (Tsumcorp Mine) in Tsumeb , Oshikoto Region , Namibia . The exact location within the Tsumeb Mine is not known.

use

Because of its rarity, barness is only of interest to mineral collectors.

See also

literature

  • Paul Keller, Heinz Hess, Pete J. Dunn: Bartelkeit, PbFe 2+ Ge 3 O 8 , a new germanium mineral from Tsumeb, Namibia . In: Chemistry of the Earth . tape 40 , 1981, ISSN  0009-2819 , pp. 201-206 .

Web links

Individual evidence

  1. ↑ a b c d e f g h i Marcus J. Origlieri, Hexiong Yang, Robert T. Downs, Esther S. Posner, Kenneth J. Domanik, William W. Pinch: The crystal structure of bartelkeite, with a revised chemical formula, PbFeGe VI (Ge 2 IV O 7 ) (OH) 2 · H 2 O, isotypic with high-pressure P 2 1 / m lawsonite . In: The American Mineralogist . tape 97 , 2012, p. 1812–1815 , doi : 10.2138 / am.2012.4269 ( rruff.info [PDF; 440 kB ; accessed on August 28, 2019]).
  2. ↑ a b c d e f g h i j k Paul Keller , Heinz Hess, Pete J. Dunn : Bartelkeit, PbFe 2+ Ge 3 O 8 , a new germanium mineral from Tsumeb, Namibia . In: Chemistry of the Earth . tape  40 , 1981, ISSN  0009-2819 , pp. 201-206 .
  3. ^ Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p.  716 (English).
  4. ↑ a b Georg Gebhard: Tsumeb . 1st edition. GG Publishing, Grossenseifen 1999, p. 275, 322 .
  5. ↑ Wolfgang Bartelke: The ore deposit of Tsumeb / South West Africa and its minerals . In: The opening . tape 27 , 1976, p. 393-439 .
  6. ^ Paul Keller , Wolfgang Bartelke: Tsumeb! new minerals and their associations . In: The Mineralogical Record . tape  13 , 1982, ISSN  0009-2819 , pp. 137-147 .
  7. ↑ R. Kurtz: Type Mineral Catalog Germany - Bartelkeit. In: typmineral.uni-hamburg.de. University of Hamburg , December 8, 2017, accessed on August 28, 2019 .
  8. ↑ Catalog of Type Mineral Specimens - B. (PDF 122 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, accessed August 28, 2019 .
  9. ↑ Nausea . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 (English, handbookofmineralogy.org [PDF; 340  kB ; accessed on August 28, 2019]).
  10. ↑ Localities for Bartelkeite. In: mindat.org. Hudson Institute of Mineralogy, accessed August 28, 2019 .
  11. ↑ Find location list for barbarity at the Mineralienatlas and at Mindat