Kakoxen

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Kakoxen
Cacoxenite-94189.jpg
radial-beam Kakoxen - location: "El Horcajo Mine" near Minas de Horcajo, Spain - image size: 3 mm
General and classification
chemical formula (Fe 3+ ) 24 AlO 6 (PO 4 ) 17 (OH) 12  • 75 H 2 O
Mineral class
(and possibly department) 		Phosphates, arsenates and vanadates
System no. to Strunz
and to Dana 		8.DC.40 ( 8th edition : VII / D.11)
42.13.05.01
Crystallographic Data
Crystal system hexagonal
Crystal class ; symbol hexagonal-dipyramidal 6 / m
Space group P 6 3 / m
Lattice parameters a  = 27.559  Å ; c  = 10.550 Å
Formula units Z  = 2
Physical Properties
Mohs hardness 3 to 4
Density (g / cm 3 ) 2.2 to 3.6
Cleavage no
Break ; Tenacity uneven
colour light yellow to brownish yellow, orange
Line color pale yellow
transparency transparent to translucent
shine Silky gloss
Crystal optics
Refractive indices n ω  = 1.575 to 1.585
n ε  = 1.635 to 1.656
Birefringence δ = 0.060
Optical character uniaxial positive

Kakoxen is a rare mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the hexagonal crystal system with the chemical composition (Fe 3+ ) 24 AlO 6 (PO 4 ) 17 (OH) 12  • 75 H 2 O and develops needle-like to fibrous, often radial mineral aggregates and crusty coatings from light yellow to brownish-yellow or orange color.

Etymology and history

Kakoxen was first found in 1825 in the "Hrbek mine" near St. Benigna ( Svatá Dobrotivá ) / Beroun in the Czech Republic and described by J. Steinmann, who composed the mineral according to the ancient Greek words κăκός for “bad” and ζέυος for “guest” So "bad guest" due to the fact that iron ores mixed with kakoxes and the pig iron made from them were of poor quality due to the increased phosphorus content .

classification

In the old (8th edition) and new systematics of minerals according to Strunz (9th edition) , the kakoxen belongs to the division of "water-containing phosphates with foreign anions ". However, the new Strunz'sche mineral classification now subdivides more precisely according to the size of the cations and the molar ratio of the other anions to the phosphate complex . The mineral is accordingly in the subsection “With only medium-sized cations; (OH etc.): RO 4  = 1: 1 and <2: 1 “.

The systematics of minerals according to Dana , which is common in the English-speaking world , assigns the kakoxes to the division of " water-containing phosphates etc., with hydroxyl or halogen ", where the mineral is the only member of the unnamed group "42.13.5" to be found.

Education and Locations

Kakoxen as a crusty coating from Oberroßbach, Wetterau, Germany

Kakoxen forms through hydrothermal processes in fissures of sedimentary iron ores , but also as a secondary mineral through weathering of primary phosphate minerals in granitic pegmatites . Accompanying minerals include beraunite , dufrénite , magnetite , rockbridge , strictite and wavellite .

So far, Kakoxen has been found at around 220 sites (as of 2009), including New South Wales , Queensland , South Australia and Victoria in Australia; Hainaut , Liège , Luxembourg and Namur in Belgium; Galiléia / Minas Gerais in Brazil; in the Rhodope Mountains in Bulgaria; in several regions of Germany and France ; England and Wales in Great Britain; in County Limerick of Ireland; Piedmont and Sardinia in Italy; on Honshū in Japan; in the Adamaua highlands in Cameroon; in Ontario , Canada ; Durango in Mexico; in the Erongo region in western Namibia; Salzburg and Styria in Austria; in the Portuguese districts of Évora , Guarda , Viana do Castelo and Viseu ; Lapland in Sweden; Banská Bystrica in Slovakia; in several regions of Spain ; Bohemia and Moravia in the Czech Republic; in the Hungarian county of Borsod-Abaúj-Zemplén ; in the Artigas department in Uruguay; as well as in many regions of the United States .

Crystal structure

Kakoxen crystallizes hexagonally in the space group P 6 3 / m with the lattice parameters a  = 27.559  Å and c  = 10.550 Å as well as two formula units per unit cell .

See also

Individual evidence

  1. ↑ a b c d Handbook of Mineralogy - Cacoxenite (English, PDF 565.7 kB).
  2. ↑ a b American Mineralogist Crystal Structure Database - Cacoxenite (English, 1983)
  3. ↑ a b Cacoxenite at mindat.org (English)
  4. ↑ IMA / CNMNC List of Mineral Names - Cacoxenite (English, PDF 1.8 MB).
  5. ↑ J. Steinmann: Archive for the entire study of nature . Ed .: Dr. Karl Wilhelm Gottlob Kastner . tape 8 . Nuremberg 1826. (available online from Google book search ).
  6. ↑ Mindat - Localities for Cacoxenite .
  7. ↑ American Mineralogist Crystal Structure Database - Cacoxenite (English, 1983).

literature

Web links

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