Diabolicity
| Diabolicity | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Pb 2 Cu (OH) 4 Cl 2 |
|
Mineral class (and possibly department) |
Halides |
|
System no. to Strunz and to Dana |
3.DB.05 ( 8th edition : III / D.12) 06/10/01/01 |
| Crystallographic Data | |
| Crystal system | tetragonal |
| Crystal class ; symbol | ditetragonal-pyramidal; 4 mm |
| Space group | P 4 mm (No. 99) |
| Lattice parameters | a = 5.88 Å ; c = 5.50 Å |
| Formula units | Z = 1 |
| Frequent crystal faces | tabular after {001} |
| Physical Properties | |
| Mohs hardness | 2.5 |
| Density (g / cm 3 ) | measured: 5.42; calculated: 5.48 |
| Cleavage | completely after {001} |
| Break ; Tenacity | shell-like, brittle |
| colour | dark blue to bright sky blue |
| Line color | Light Blue |
| transparency | transparent to translucent |
| shine | Diamond luster, pearl luster on the cleavage surfaces |
| Crystal optics | |
| Refractive indices |
n ω = 1.980 n ε = 1.850 |
| Birefringence | δ = 0.130 |
| Optical character | uniaxial negative |
Diaboleit is a rarely occurring mineral from the mineral class of halides . It crystallizes in the tetragonal crystal system with the chemical composition Pb 2 Cu (OH) 4 Cl 2 and develops mostly transparent to translucent crystals with a tabular to prismatic habit and square or octagonal costume , but also massive aggregates of dark blue to bright sky blue in color with light blue streak color .
Unharmed crystal surfaces have a diamond-like sheen , whereas cleavage surfaces tend to have a mother-of-pearl-like sheen.
Etymology and history
The mineral was named after the Greek word διά [Dia] for apart or different in allusion to its relationship to Boleit , from which it nevertheless clearly differs due to its crystal shape.
Diaboleit was first discovered in the "Higher Pitts Mine" near Priddy in the English county of Somerset . It was described and named in 1923 by Leonard James Spencer (1870–1959) and Edgar Donald Mountain (1901–1985), who analyzed the composition.
Type material of the mineral is in the Natural History Museum of London under the register no. 1923,521 as well as in the National Museum of Natural History in Washington DC in the USA under the register no. 94813 kept.
classification
In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the diabolite belonged to the mineral class of the "halides" and there to the department of the "oxyhalides", where together with bideauxite , boleit , chloroxiphite , cumengeit , hematophanite , pseudoboleit and yedlinite formed an independent group.
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), assigns the Diaboleit to the class of "halides" and there to the department of "oxyhalides, hydroxyhalides and related double halides". However, this section is further subdivided according to the type of metals involved, so that the mineral can be found according to its composition in the sub-section “With Pb, Cu etc.”, where it is the only member of the unnamed group 3.DB.05 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the diabolite to the class of "halides" and there in the department of "oxyhalides and hydroxyhalides". Here he is the only member of the unnamed group 10.06.01 within the subdivision of " Oxihalides and hydroxyhalides with the formula A m B n (O, OH) p X q ".
Crystal structure
Diaboleit crystallizes tetragonally in the space group P 4 mm (space group no. 99) with the lattice parameters a = 5.88 Å and c = 5.50 Å as well as one formula unit per unit cell .
Education and Locations
Diaboleit forms as a secondary mineral in heavily weathered manganese - or lead - and copper-containing ores . Accompanying minerals include atacamite , boleit , caledonite , chloroxiphite , cerussite , hydrocerussite , leadhillite , mendipite , paratacamite , phosgenite and wherryite .
So far (as of 2011) Diaboleit could be detected at around 50 sites worldwide. In addition to its type locality Priddy, the mineral was also found in the Mendip Hills , at Holwell , Cranmore and Cheddar in the county of Somerset and at Padstow and Crantock in the county of Cornwall .
In Germany, the mineral appeared in a slag field near Richelsdorf in Hesse, near Astfeld in Lower Saxony and in the Christian Levin colliery in North Rhine-Westphalia. In Austria, the mineral has so far only been found in a slag field near Waitschach in Carinthia.
Other locations are Australia , Chile , France , Greece , Iran , Italy , South Africa and the United States of America (USA).
See also
literature
- Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 496 (first edition: 1891).
Web links
- Mineral Atlas: Diaboleit (Wiki)
- RRUFF Database-of-Raman-spectroscopy - Diaboleite (English)
- Handbook of Mineralogy - Diaboleite (English, PDF 130.8 kB)
Individual evidence
- ↑ a b c d e 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 .
- ↑ Webmineral - Diaboleite (English)
- ↑ a b c Mindat - Diaboleite (English)
- ^ CE Tilley: Memorial of Leonard James Spencer . In: The American Mineralogist . tape 45 , 1960, pp. 403–406 ( minsocam.org [PDF; 288 kB ; accessed on February 8, 2018]).
- ↑ Minéraux et étymologie from February 28, 2009 (Mountainite named after Prof. Edgar Donald Mountain (1901-1985), Geologue et Mineralogiste anglais )
- ^ LJ donor: New Lead-Copper Minerals from the Mendip Hills (Somerset) . In: Journal of the Chemical Society, Abstracts . tape 124 , 1923, pp. ii774 , doi : 10.1039 / CA9232405774 ( rruff.info [PDF; 1,4 MB ; Retrieved February 8, 2018] with analysis by ED Mountain).