Kolbeckite

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Kolbeckite
Kolbeckite-215064.jpg
Globular, green Kolbeckite from the Schlarbaum quarry, Bad Gleichenberg , Styria, Austria ( overall size : 4.9 cm × 3.9 cm × 2.3 cm)
General and classification
other names
  • Eggonite
  • Sterretite or sterrettite (mainly in the US-American language area)
  • Scandium phosphate dihydrate
chemical formula Sc [PO 4 ] • 2H 2 O
Mineral class
(and possibly department) 		Phosphates, arsenates and vanadates
System no. to Strunz
and to Dana 		8.CD.05 ( 8th edition : VII / C.09)
04/40/03/03
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group P 2 1 / n (No. 14, position 2)Template: room group / 14.2
Lattice parameters a  = 5.42  Å ; b  = 10.19 Å; c  = 8.89 Å
β  = 90.8 °
Formula units Z  = 4
Frequent crystal faces {110}, {011}
Twinning after {100} pseudo-rhombohedral twins
Physical Properties
Mohs hardness 3.5 to 4
Density (g / cm 3 ) measured: 2.36 to 2.39; calculated: 2.35
Cleavage clear after {010}, indistinct after {100} and {001}
Break ; Tenacity clamshell; brittle
colour colorless, blue-gray, cyan , light yellow, apple green
Line color White
transparency transparent
shine Glass gloss to pearlescent
Crystal optics
Refractive indices n α  = 1.572 to 1.575
n β  = 1.590
n γ  = 1.598 to 1.601
Birefringence δ = 0.026
Optical character biaxial negative
Axis angle 2V = measured: 60 °; calculated: 74 °
Pleochroism strong: but only with colored samples

Kolbeckite , also known as eggonite or sterretite or sterrettite , is a rarely occurring mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the monoclinic crystal system with the chemical composition Sc [PO 4 ] · 2H 2 O, so it is a water-containing scandium phosphate and besides the waterless pretulite (Sc [PO 4 ]) the only known phosphate mineral with scandium as the main component.

Kolbeckite develops tabular to short prismatic crystals , which are usually arranged in radial or spherical mineral aggregates and show a glass-like to mother-of-pearl-like gloss on the surface. Also known are twinned crystals with pseudo- rhombohedral crystal form. In its pure form, Kolbeckite is colorless and transparent. However, due to multiple refraction due to lattice construction defects or polycrystalline training, it can also appear white and, due to foreign admixtures , take on a light yellow, cyan , blue-gray or apple-green color, with the transparency decreasing accordingly. However, its line color is always white.

With a Mohs hardness of 3.5 to 4, kolbeckite is one of the medium-hard minerals that, like the reference mineral fluorite, can be easily scratched with a pocket knife .

Etymology and history

The mineral was first discovered in 1908 by Mr. Morgenstern, director of the "Kupfergrübner Stolln" near Sadisdorf in the Saxon town of Dippoldiswalde , who noticed it on the snow-covered dump of the mine because of its strong blue color. Since the color of the mineral resembled the apatites that frequently occur in the area , but without showing their crystal shape, Morgenstern sent the crystal to Friedrich Ludwig Wilhelm Kolbeck (1860–1943) at the Bergakademie Freiberg , who immediately identified it as a previously unknown, new type of mineral recognized. However, since he did not find enough material for a precise analysis despite his own search on the heaps, he was only able to determine the crystal system (monoclinic) and the density (≈2.39 g / cm³).

An at least qualitative, albeit imprecise, analysis of the mineral was achieved in 1911 by the chemist Theodor Döring (1873–1947), professor of applied chemistry at the University of Freiberg, who contained a lot of beryllium (Be), very little aluminum (Al) and magnesium (Mg) as well as P 2 O 5 , SiO 2 and traces of copper (Cu), iron (Fe) and SO 3 found, but no scandium. He therefore thought the mineral was a beryllium phosphate or a silicophosphate of beryllium.

In 1926, in his description of the mineral found by Morgenstern, the engineer F. Edelmann mentioned, in addition to some optical and physical properties, the analysis by Döring and named it Kolbeckite after Friedrich Kolbeck. A more precise chemical composition can not be found in the "Yearbook for Mining and Metallurgy in Saxony" published in the same year.

Another chemical analysis of the material from Sadisdorf followed in 1932 by H. Thurnwald and AA Benedetti-Pichler. They overlooked the scandium and mistook the mineral for a Be-Al-Ca silicon phosphate. The correct chemical composition with Sc [PO 4 ] · 2H 2 O was not known until 1965 by Mary E. Mrose via a short communication with reference to unpublished analysis data.

Already in 1879 Albrecht Schrauf described a mineral from Altenberg near Aachen , similar to Kolbeckite , which he called Eggonite . In 1892, however, he himself discredited his mineral description in a communication to Dana after he had discovered that it was a matter of fake mineral specimens. Another mineral, similar to Kolbeckite, was described in 1940 by Esper S. Larsen and Arthur Montgommery, which they found near Fairfield , Utah , and designated it as sterrettite (after Douglas B. Sterrett, who examined the variscite deposits in Utah and Nevada) . A year later, however, FA Bannister was able to use X-ray analysis to prove that eggonite and sterretite are identical. In 1959, Mary E. Mrose and B. Wappner also determined, also by X-ray analysis, that sterretite and eggonite are largely identical to the Kolbeckite from Sadisdorf and the synthetically produced ScPO 4 · 2H 2 O.

Due to the manifold problems with the chemical analyzes and different mineral names, the IMA / CNMNC finally decided, first in 1965 and finally again in 1987, that the mineral with the composition Sc [PO 4 ] · 2H 2 O should be named Kolbeckite.

There is also a risk of confusion due to the similarity of the name with the mineral herzbergite, which is synonymous with Kolbeckin .

classification

Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , Kolbeckite belonged to the class of "phosphates, arsenates and vanadates" and there to the department of "water-containing phosphates without foreign anions ", where it together with Koninckit , Malhmoodit , Mansfieldite , metavariscite , parascorodite , phosphosiderite , scorodite , strictite , variscite and yanomaite the "variscite group" with the system no. VII / C.09 formed.

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns Kolbeckite to the category of “phosphates etc. without additional anions; with H 2 O “. However, this is further subdivided according to the relative size of the cations involved and the molar ratio of the phosphate, arsenate or vanadate complex (RO 4 ) to the water of crystallization content , so that the mineral can be classified according to its composition in the subsection “With only medium-sized cations; RO 4  : H 2 O = 1: 2 "can be found where, together with metavariscite and phosphosiderite, the" metavariscite group "with the system no. 8.CD.05 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Kolbeckite to the class of "phosphates, arsenates and vanadates" and there to the department of "water-containing phosphates etc.". Here it is also together with metavariscite and phosphosiderite in the " metavariscite group " with the system no. 04/40/03 to be found in the subsection “Phosphates containing water, with A 3+ XO 4  × x (H 2 O)”.

Crystal structure

Kolbeckite crystallizes isotypically with phosphosiderite in the monoclinic crystal system in the space group P 2 1 / n (space group no. 14, position 2) with the lattice parameters a  = 5.42  Å ; b  = 10.19 Å; c  = 8.89 Å and β = 90.8 ° as well as four formula units per unit cell . Template: room group / 14.2

The crystal structure of Kolbeckite consists of PO 4 - tetrahedra and ScO 4 (H 2 O) 2 - octahedra , which are linked by their corners and thus form a three-dimensional framework.

Education and Locations

Pseudo-rhombohedral Kolbeckite from the "Union Carbide Christy Vanadium Mine", Magnet Cove , Hot Spring County , Arkansas, USA (field of view 1.5 mm)

Kolbeckit formed secondarily in some hydrothermal - veins and phosphate deposits . Depending on the locality, the mineral can with chlorite , Crandallit , gypsum , Diaphorit (not to be confused with Diaspor !), Lithiophorit , Malhmoodit , Miargyrit , quartz , Variscit , vernadite and / or Wardit socialized to be.

As a rare mineral formation, Kolbeckite could only be detected at a few sites, with around 20 sites being known so far (as of 2013). Besides its type locality Sadisdorf in Saxony the mineral occurred in Germany nor in Trutzhofmühle in the municipality Pleystein and Hagensdorf in the market town of Waidhaus in Bavaria and in the pit "Pius" in Schutzbach and the Pit "Nice view" in Dernbach (district of Neuwied) in Rhineland-Palatinate.

The only known site in Austria so far is the "Schlarbaum" quarry near Klausen ( Bad Gleichenberg municipality ) in Styria.

Other well-known sites include Putty Beach on the Woy Woy peninsula in the Australian state of New South Wales , Krásno nad Teplou (German Schönfeld ) and Těškov in the Czech Republic, the Shinkolobwe mine in the Democratic Republic of the Congo, Vatukoula on the Fiji island of Viti Levu , Bric Colmè near San Giacomo in the municipality of Roburent in the Italian province of Cuneo , Mrima Hill in the coastal province of Kenya, Bixad (Covasna) and Baia Sprie in Romania, the Sn-W-Mo deposit "Tigrinoe" (also Tigriny ) in the Russian Primorye ( Primorsky krai ) and Wilson Springs ( Garland County ) and magnetic Cove ( Hot Spring County ), Arkansas, Fairfield in the Oquirrh Mountains in Utah and Ladysmith ( Rusk County ), Wisconsin in the United States.


See also

literature

  • F. Edelmann: Kolbeckite, a new Saxon mineral . In: Yearbook for mining and metallurgy in Saxony . tape 100 , 1926, pp. 73–74 ( rruff.info [PDF; 145 kB ; accessed on November 11, 2019]).
  • Hexiong Yang, Chen Li, Robert A. Jenkins, Robert T. Downs, Gelu Costin: Kolbeckite, ScPO 4 · 2H 2 O, isomorphous with metavariscite . In: Acta Crystallographica . C63, 2007, p. i91 – i92 (English, available online at rruff.info [PDF; 159 kB ; accessed on April 23, 2019]).

Web links

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

Individual evidence

  1. ↑ a b Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties. Status 03/2018 . 7th, completely revised and supplemented edition. Weise, Munich 2018, ISBN 978-3-921656-83-9 .
  2. ↑ 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.  629 .
  3. ↑ a b Friedrich Klockmann : Klockmanns textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp.  641 (first edition: 1891).
  4. ↑ a b c d e 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.  477 .
  5. ^ David Barthelmy: Kolbeckite Mineral Data. In: webmineral.com. Retrieved November 11, 2019 .
  6. ↑ a b Kolbeckite . 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; 70  kB ; accessed on November 11, 2019]).
  7. ↑ Kolbeckite. In: mindat.org. Hudson Institute of Mineralogy, accessed November 11, 2019 .
  8. ^ Theodor Döring , chemist: Deutsche Biographische Enzyklopädie . Ed .: Rudolf Vierhaus. 2nd, revised and expanded edition. tape  2 . KG Saur Verlag, Munich 2005, p. 673 ( limited preview in Google Book Search [accessed November 11, 2019]).
  9. ^ A. Tetzner, F. Edelmann: New Saxon mineral deposits . In: Sächsisches Oberbergamt (Hrsg.): Yearbook for mining and metallurgy in Saxony . Year 1926, 1926, p. 49 ( PDF 18.3 MB ( memento of October 29, 2013 in the Internet Archive )).
  10. ^ F. Edelmann: Kolbeckite, a new Saxon mineral . In: Sächsisches Oberbergamt (Hrsg.): Yearbook for mining and metallurgy in Saxony . Year 1926, 1926, p. 73 ( rruff.info [PDF; 145 kB ; accessed on November 11, 2019]).
  11. ↑ Thomas Witzke : Discovery of Kolbeckite. Retrieved November 11, 2019 .
  12. ↑ A. Schrauf : About Eggonit . In: Journal of Crystallography, Mineralogy and Petrography . tape  3 , 1879, p. 352–356 ( available online at archive.org  - Internet Archive [accessed November 11, 2019]).
  13. ^ ES Dana : A system of mineralogy. 6th edition. New York 1892, p. 905.
  14. ↑ Mary E. Mrose, B. Wappner: New data on the hydrated scandium phosphate minerals: Sterrettite, "eggonite", and kolbeckite . In: Bulletin of the Geological Society of America . tape 70 , 1959, pp. 1648-1649 (English).
  15. ↑ Ernest H. Nickel , Joseph A. Mandarino: Procedures involving the IMA Commission on New Minerals and Mineral Names and guidelines on mineral nomenclature . In: American Mineralogist . tape  72 , 1987, pp. 1031-1042 (English, rruff.info [PDF; 1.3 MB ; accessed on November 11, 2019]).
  16. ^ Helmut Schrätze , Karl-Ludwig Weiner : Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp.  212 .
  17. ↑ Localities for Kolbeckite. In: mindat.org. Hudson Institute of Mineralogy, accessed November 11, 2019 .
  18. ↑ List of localities for Kolbeckite in the Mineralienatlas and Mindat , accessed on November 11, 2019.