Laurionite

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Laurionite
Laurionite.jpg
Laurionite crystals from Laurion , Attica (Greece)
General and classification
chemical formula Pb (OH) Cl
Mineral class
(and possibly department) 		Halides
System no. to Strunz
and to Dana 		3.DC.05 ( 8th edition : III / D.08)
02/10/02/01
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol orthorhombic-dipyramidal; 2 / m  2 / m  2 / m
Space group Pcmn (No. 62, position 4)Template: room group / 62.4
Lattice parameters a  = 9.70  Å ; b  = 4.02 Å; c  = 7.11 Å
Formula units Z  = 4
Physical Properties
Mohs hardness 3 to 3.5
Density (g / cm 3 ) measured: 6.241; calculated: 6.212
Cleavage clearly after {101}
Break ; Tenacity flexible
colour colorless, white
Line color White
transparency transparent
shine Diamond luster, pearlescent luster according to {100}
Crystal optics
Refractive indices n α  = 2.077
n β  = 2.116
n γ  = 2.158
Birefringence δ = 0.081
Optical character biaxial negative
Axis angle 2V = measured: 70 °; calculated: 90 °

Laurionite is a mineral from the mineral class of halides . It crystallizes in the orthorhombic crystal system with the chemical composition Pb (OH) Cl and develops only colorless or white, tabular to thin-prismatic crystals of mostly conspicuous angular shape up to one centimeter in length.

Etymology and history

Laurionite was first found in 1887 at various slag discovery sites in the area around Laurion in the Greek region of Attica and described by Rudolf Koechlin (1862–1939), who named the mineral after its type of locality .

classification

In the old (8th edition) and new systematics of minerals according to Strunz (9th edition) , the laurionite belongs to the division of oxyhalides (and related double halides). The new Strunz'sche mineral system, however, now subdivides more precisely according to the cations involved in the formula and the mineral is accordingly in the sub-section “With Pb (As, Sb, Bi) without Cu”.

The systematics of minerals according to Dana also assigns the laurionite to the oxyhalides, but according to the classification according to chemical composition in the subdivision "Oxyhalides and hydroxyhalides with the formula A (O, OH) X q " .

Crystal structure

Laurionite crystallizes in the space group Pcmn (space group no. 62, position 4) with the lattice parameters a  = 9.70  Å ; b  = 4.02 Å and c  = 7.11 Å as well as four formula units per unit cell . Template: room group / 62.4

Education and Locations

Laurionite is formed on the one hand in ancient, lead-containing slag produced by metal processing under the influence of salt water , but on the other hand as a secondary mineral in the oxidation zone of lead-containing mineral deposits . Accompanying minerals include angelsite , cerussite , fiedlerite , paralaurionite , penfieldite and phosgenite .

As a rare mineral formation, laurionite could only be detected in a few places, whereby so far (as of 2016) around 50 sites are known. At its type locality Lavrio, laurionite was found in many slag heaps in the area.

In Germany, the mineral has been found on slag heaps near Richelsdorf in Hesse, Astfeld in Lower Saxony, the former municipality of Kall (now Mechernich ) in North Rhine-Westphalia and Braubach in Rhineland-Palatinate, as well as in the Christian Levin colliery near Essen and the Auguste Victoria colliery at Marl-Hüls in North Rhine-Westphalia.

The only known site in Austria so far is a slag dump near Waitschach (Hüttenberg municipality) in Carinthia.

Other locations are in Australia, France, Israel, Italy, Canada, South Africa, the Czech Republic, Tunisia, Turkmenistan, the United Kingdom (UK) and the United States of America (USA).

See also

literature

Web links

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

Individual evidence

  1. ↑ 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.  175 .
  2. ↑ a b c d Laurionite , 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 )
  3. ↑ a b c d e Mindat - Laurionite
  4. ↑ Mindat - Number of localities for laurionite
  5. ↑ Find location list for laurionite in the Mineralienatlas and in Mindat - Localities for Laurionite