Leadhillit

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Leadhillit
Leadhillite-189253.jpg
from Leadhills , South Lanarkshire, Scotland
General and classification
chemical formula Pb 4 [(OH) 2 | (CO 3 ) 2 | SO 4 ]
Mineral class
(and possibly department) 		Anhydrous carbonates with other anions
System no. to Strunz
and to Dana 		5.BF.40 ( 8th edition : VI / B.13)
01/17/02/01
Similar minerals Susannite , macphersonite
Crystallographic Data
Crystal system monoclinic, pseudohexagonal
Crystal class ; symbol monoclinic prismatic 2 / m
Space group P 2 1 / a
Lattice parameters a  = 9.104  Å ; b  = 20.792 Å; c  = 11.577 Å
β  = 90.50 °
Formula units Z  = 8
Twinning often after {140}, {340} and {140}
Physical Properties
Mohs hardness 2.5 to 3
Density (g / cm 3 ) 6.26 to 6.55
Cleavage completely after {001}, indistinct after {100}
Break ; Tenacity shell-like
colour colorless, white, gray-yellow, pale blue
Line color White
transparency transparent to translucent
shine Resin gloss to diamond gloss
Crystal optics
Refractive indices n α  = 1.870
n β  = 2.009
n γ  = 2.010
Birefringence δ = 0.140
Optical character biaxial negative
Axis angle 2V = 10 °
Other properties
Chemical behavior soluble in nitric acid
Special features fluorescence

Leadhillite is a rarely occurring mineral from the mineral class of carbonates (and nitrates). It crystallizes in the monoclinic crystal system with the chemical composition Pb 4 [(OH) 2 | (CO 3 ) 2 | SO 4 ] and develops predominantly pseudo-hexagonal, tabular crystals , which can be either colorless or white, gray-yellow or pale blue due to foreign admixtures. Shell aggregates are also rarely found .

Special properties

Since leadhillite is isomorphic with susannite and macphersonite , it also has comparable properties. Some levels show a strong lemon yellow fluorescence under UV light . When heated on charcoal in front of the soldering tube , leadhillite swells a little, turns yellow and reduces to lead. In nitric acid , the mineral dissolves with a fizz, releasing carbon dioxide . The poorly soluble lead sulfate that remains forms a white precipitate .

Etymology and history

Leadhillit was first discovered and described in 1832 by François Sulpice Beudant , who named it Leadhills ("Susannah Mine") in Scotland after its type locality .

classification

In the old systematics of minerals (8th edition) according to Strunz , the lead hillite was sorted into the section of "Anhydrous sulfates with foreign anions ". However, since the new systematics of minerals (9th edition) (according to Strunz), the mineral has been re-classified and can now be found in the section of "Carbonates with other anions, without H 2 O with Cl, SO 4 , PO 4 ".

In the systematics of minerals according to Dana , Leadhillit is in the department of “Compound Carbonates with miscellaneous formulas” (translated: carbonates with diverse compositions ).

Education and Locations

Leadhillit forms as a typical secondary mineral primarily in the oxidation zone of lead - deposits and there occurs in Paragenesis with Anglesit , Cerussit , Linarit and other secondary lead minerals on.

Locations include New South Wales , Queensland and Tasmania in Australia; the provinces of Limburg and Luxembourg in Belgium; Baden-Württemberg (Black Forest), Lower Saxony (St. Andreasberg), North Rhine-Westphalia (Bergisches Land, Siegerland), Rhineland-Palatinate (Eifel), Saxony-Anhalt (Harz) and Saxony (Ore Mountains) in Germany; different regions in France ; Attica in Greece; different regions in the UK ; different regions in Italy ; Kyushu in Japan; Oshikoto and Otjozondjupa in Namibia; Carinthia and Styria in Austria; Eastern Siberia , Murmansk Oblast and the Urals in Russia; the cantons of Uri and Valais in Switzerland; Gauteng and the North Cape in South Africa; Bohemia in the Czech Republic; as well as various regions in the US .

Crystal structure

Leadhillite crystallizes in the monoclinic crystal system in the space group P2 1 / a with the lattice parameters a = 9.104  Å , b = 20.792 Å, c = 11.577 Å and β = 90.50 °, as well as eight formula units per unit cell .

See also

Individual evidence

  1. ↑ a b Webmineral - Leadhillite (English)
  2. ↑ a b American Mineralogist Crystal Structure Database - Leadhillite (engl., 2005)
  3. ↑ a b c d Leadhillite at mindat.org (engl.)
  4. ↑ Stefan Weiß: The large Lapis mineral directory . 5th edition. Christian Weise Verlag, Munich 2008, ISBN 3-921656-17-6 .
  5. ↑ Leadhillit (and Susannit) , in: CF Rammelsberg (ed.): Handbuch der Mineralchemie , Verlag von Wilhelm Engelmann, Leipzig 1860, p. 297
  6. ↑ MinDat - Localities for Leadhillite (English)
  7. ↑ American Mineralogist Crystal Structure Database - Leadhillite (2005)

literature

  • Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 142 .

Web links

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