Bayldonite
| Bayldonite | |
|---|---|
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|
| General and classification | |
| chemical formula | PbCu 3 [OH | AsO 4 ] 2 |
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.BH.45 ( 8th edition : VII / B.33) 05.41.14.01 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | 2 / m |
| Room group (no.) | C 2 / c (No. 15) |
| Lattice parameters |
a = 10.15 Å ; b = 5.89 Å; c = 14.08 Å β = 106.1 ° |
| Formula units | Z = 4 |
| Twinning | rarely pseudo-hexagonal triplets |
| Physical Properties | |
| Mohs hardness | 4.5 |
| Density (g / cm 3 ) | 5.24 to 5.65 |
| Cleavage | is missing |
| Break ; Tenacity | irregular |
| colour | grass green, dark green |
| Line color | green |
| transparency | transparent |
| shine | resinous |
| Crystal optics | |
| Refractive indices |
n α = 1.950 n β = 1.970 n γ = 1.990 |
| Birefringence | δ = max. 0.040 |
| Axis angle | 2V = 89 ° |
Bayldonite is a seldom occurring mineral from the mineral class of phosphates , arsenates and vanadates . It crystallizes in the monoclinic crystal system with the chemical formula PbCu 3 [OH | AsO 4 ] 2 and usually forms powdery coatings, rarely crystals up to one centimeter in size in the form of pseudo-hexagonal triplets .
Etymology and history
Bayldonite was first found in 1865 by British physicist John Bayldon in the type locality , the Penberthy Croft Mine near St Hilary in Cornwall , England . It was described in more detail by Arthur Herbert Church , who named it after its discoverer.
classification
In the Strunz system , bayldonite is classified as phosphates, arsenates and vanadates. It is counted among the phosphates, arsenates and vanadates with other anions , but without crystal water . While it forms a separate group in the eighth edition , in the ninth edition bayldonite, leningradite and vésigniéit become a subgroup of phosphates, arsenates and vanadates with medium-sized and mostly large cations (OH etc.) and a ratio of anions and RO 4 of 1: 1 summarized.
In the systematics of minerals according to Dana it forms a subgroup of the anhydrous phosphates etc. with hydroxyl or halogen ions and a composition (AB) 2 (XO 4 ) Z q .
Education and Locations
Bayldonite forms as a secondary mineral in the oxidative zone of lead-copper deposits. It is associated with mimetesite , beudantite , fragranceite , pharmacosiderite , goethite , segnitite and mixite .
As a rather rare mineral formation, bayldonite can be partly abundant at different sites, but overall it is not very common. So far (as of 2011) around 160 sites are known.
In Europe, Bayldonite can be found in several places in England ( Cornwall , Cumbria ), especially in Germany ( Black Forest ) and France , individual finds are also known from other European countries. Outside of Europe, Bayldonite is known from the United States , Australia and Kazakhstan , among others . Larger crystals are mainly found in Tsumeb in Namibia .
Crystal structure
Balydonite crystallizes in the monoclinic crystal system in the space group C 2 / c (space group no. 15), the lattice parameters a = 10.15 Å , b = 5.89 Å, c = 14.08 Å and β = 106.1 ° as well four formula units per unit cell .
See also
Individual evidence
- ↑ a b c d e Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 459 .
- ↑ AH Church: XLI. Chemical researches on some new and rare minerals cornish . In: Journal of the Chemical Society , 1865, 18, pp. 259-268, doi : 10.1039 / JS8651800259 .
- ^ List of minerals according to Dana at webmineral.com
- ↑ Mindat - Number of localities for Bayldonite
literature
- Bayldonit in: Anthony et al .: Handbook of Mineralogy , 1990, 1, 101 ( pdf )
