Kuzelit

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Kuzelit
Kuzelite - Bellerberg, Eifel, Germany.jpg
Shiny mother-of-pearl kuzelite from Bellerberg in the Eifel
General and classification
other names

IMA 1996-053

chemical formula Ca 4 Al 2 (OH) 12 (SO 4 ) • 6H 2 O
Mineral class
(and possibly department) 		Oxides and hydroxides
System no. to Strunz
and to Dana 		4.FL.15 ( 8th edition : IV / F.10)
04/06/12/01
Crystallographic Data
Crystal system trigonal
Crystal class ; symbol trigonal-pyramidal; 3
Space group R 3 (No. 148)Template: room group / 148
Lattice parameters a  = 5.76  Å ; c  = 53.66 Å
Formula units Z  = 3
Physical Properties
Mohs hardness 1 to 2
Density (g / cm 3 ) measured: 1.99; calculated: 2.014
Cleavage completely after {0001}
Break ; Tenacity uneven
colour colorless, white, pale yellow
Line color White
transparency transparent
shine Glass luster, mother-of-pearl luster on the fracture surfaces
Crystal optics
Refractive indices n ω  = 1.504
n ε  = 1.485
Birefringence δ = 0.019
Optical character uniaxial negative
Other properties
Chemical behavior Easily soluble in ENT 3

Kuzelite is a very rarely occurring mineral from the mineral class of "oxides and hydroxides" with the chemical composition Ca 4 Al 2 (OH) 12 (SO 4 ) · 6H 2 O and is therefore chemically a water-containing calcium - aluminum - hydroxide with additional Sulfate ions .

Kuzelite crystallizes in the trigonal crystal system , but develops only very small, tabular crystals up to about 2 mm in size with a hexagonal or rhombohedral habit and a glass-like sheen on the surfaces. In its pure form, kuzelite 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 pale yellow color, the transparency decreasing accordingly. His line color , however, is always white.

Etymology and history

Kuzelit was first found in 1996 on the Zeilberg near Maroldsweisach in the Bavarian district of Lower Franconia . The mineral was scientifically described by Herbert Pöllmann , Thomas Witzke and H. Kohler, who named it after Hans-Jürgen Kuzel (1932–1997). He was a mineralogist and university professor at the Mineralogical Institute in Erlangen and for the first time synthesized the chemical compound of the kuzelite.

The complete mineral description and the chosen name were submitted to the International Mineralogical Association for examination (IMA entry number: 1996-053 ), which recognized the mineral as an independent mineral type in the same year. The first description was published in the following year in the science magazine Neues Jahrbuch für Mineralogie, Monatshefte .

The holotype material of the mineral is stored in the mineralogical collection of the Martin Luther University Halle-Wittenberg in Saxony-Anhalt, Germany under catalog no. 001 HSUL kept.

classification

Already in the outdated but still partially in use 8th edition of the mineral classification by Strunz of Kuzelit the mineral class of "oxides and hydroxides" and then to the department belonged "hydroxides and oxide hydrates (hydrous oxides with layered structure)" where he collaborated with Hydrocalumit the unnamed group IV / F.10 formed.

The 9th edition of Strunz's mineral systematics, valid since 2001 and used by the International Mineralogical Association (IMA), classifies the kuzelite in the newly defined division of "hydroxides (without V or U)". This is further subdivided according to the possible presence of crystal water (H 2 O) and the crystal structure, so that the mineral according to its composition and structure in the sub-section “Hydroxides with H 2 O ± (OH); Layers of edge-linked octahedra "can be found, where it is the only member of the unnamed group 4.FL.15 .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns kuzelite to the class of "oxides and hydroxides" and there in the category of "hydroxides and hydroxides containing oxides". Here he is to be found as the only member of the unnamed group 04/06/12 within the sub-section "Hydroxides and hydroxides containing various cations".

Chemism

The electron beam microanalysis and the wet chemical analysis showed an average content of 34.5% by weight CaO , 19.6% by weight Al 2 O 3 , 12.9% by weight SO 3 and 33.45% by weight H 2 O, which corresponds to the empirical formula Ca 3.83 Al 2.40 (OH) 12.86 (SO 4 ) · 6H 2 O with a proportion of one molecule of SO 4 .

Crystal structure

Kuzelite crystallizes trigonal in the space group R 3 (space group no. 148) with the lattice parameters a  = 5.76  Å and c  = 53.66 Å as well as 3 formula units per unit cell . Template: room group / 148

Education and Locations

In rare cases, kuzelite forms in carbon-containing xenolites in basalt at over 100 ° C through the transformation of ettringite . Depending on where it was found, it occurs in paragenesis with various minerals, so in addition to ettringite, among others, afwillite , apophyllite , calcite , gypsum , hydrocalumite , natrolite , gyrolite , portlandite and torbermorite .

So far (as of 2018) only four sites have been documented for Kuzelit worldwide, all of which are in Germany. In addition to its type locality Zeilberg in Bavaria, these are the Caspar quarry and the Seekante (term for the eastern part of a lava flow) on Ettringer Bellerberg near Ettringen (Eifel) and the quarry on Rothenberg near Bell in Rhineland-Palatinate.

Kuzelit can also be produced synthetically when cement sets .

See also

literature

  • Herbert Pöllmann , Thomas Witzke , H. Kohler: Kuzelite, [Ca 4 Al 2 (OH) 12 ] [(SO 4 ) 3 · 6H 2 O], a new mineral from Maroldsweisach / Bavaria, Germany . In: New yearbook for mineralogy - monthly books . January 1997, p. 423-432 .
  • John Leslie Jambor , Nikolai N. Pertsev, Andrew C. Roberts: New Mineral Names . In: American Mineralogist . tape 83 , 1998, pp. 907-910 ( minsocam.org [PDF; 69 kB ; accessed on May 27, 2018] Kuzelite from p. 909).

Web links

Commons : Kuzelite  - collection of pictures, videos and audio files

Individual evidence

  1. ↑ Webmineral - Kuzelite (English)
  2. ↑ a b c d 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.  244 .
  3. ↑ a b c Kuzelite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 67  kB ; accessed on May 27, 2018]).
  4. ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 6th completely revised and supplemented edition. Weise, Munich 2014, ISBN 978-3-921656-80-8 .
  5. ↑ a b c Mindat - Kuzelite (English)
  6. ^ A b John Leslie Jambor , Nikolai N. Pertsev, Andrew C. Roberts: New Mineral Names . In: American Mineralogist . tape  83 , 1998, pp. 907-910 ( minsocam.org [PDF; 69 kB ; accessed on May 27, 2018] Kuzelite from p. 909).
  7. ↑ Type mineral catalog of the University of Hamburg - Kuzelit
  8. ↑ Find location list for kuzelite at the Mineralienatlas and at Mindat