Hydrowoodwardite
| Hydrowoodwardite | |
|---|---|
 (image width: 5 mm) |
|
| General and classification | |
| other names |
IMA 1996-038 |
| chemical formula | [Cu 1-x Al x (OH) 2 ] [(SO 4 ) x / 2 (H 2 O) n ] (with x <0.67) |
|
Mineral class (and possibly department) |
Sulphates, selenates, tellurates, chromates, molybdates, tungstates |
|
System no. to Strunz and to Dana |
7.DD.35 ( 8th edition : VI / D.08) 31.02.02.02 |
| Crystallographic Data | |
| Crystal system | trigonal |
| Crystal class ; symbol | ditrigonal-pyramidal; 3 m |
| Space group | R 3 m (No. 166) |
| Lattice parameters | a = 3.07 Å ; c = 31.9 Å |
| Formula units | Z = 3 |
| Physical Properties | |
| Mohs hardness | 2 |
| Density (g / cm 3 ) | Please complete |
| Cleavage | no |
| colour | pale blue to blue |
| Line color | bluish white |
| transparency | translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n ω = 1.549 n ε = 1.565 |
| Birefringence | δ = 0.016 |
| Optical character | uniaxial positive |
Hydrowoodwardite is a rarely occurring mineral from the mineral class of " sulfates , selenates , tellurates , chromates , molybdates and wolframates ". It crystallizes in the trigonal crystal system with the chemical composition [Cu 1-x Al x (OH) 2 ] [(SO 4 ) x / 2 (H 2 O) n ] (at x <0.67) or somewhat simplified ~ [( Cu, Al) 9 (OH) 18 ] [(SO 4 ) 2 · nH 2 O] and develops predominantly pale blue to blue, grape-like or stalactitic, porous mineral aggregates and crusty coatings, whereby these crusts can reach square meter dimensions.
Hydrowoodwardite forms a mixed crystal row with glaucocerinite .
Etymology and history
Hydrowoodwardit was due to its close relationship with Woodwardite as "hydrated Woodwardite" ( hydrous Woodwardite ) named.
Hydrowoodwardite was first scientifically described in 1996 by Thomas Witzke , who submitted his results and the chosen name to the International Mineralogical Association (IMA) for examination of the mineral status (entry no .: IMA1996-038 ). This recognized the Hydrowoodwardit as independent in the same year. The research results and the recognized name Hydrowoodwardit were published in 1999 in the science magazine “New Yearbook for Mineralogy - Monthly Bulletins”.
Since material from the St. Briccius mine in the Saxon municipality of Königswalde near Annaberg was used in the analysis , this is considered a type locality . However, apart from a few interruptions, this pit was already used for mining purposes from the 15th to the 19th century for the extraction of copper , silver and tin . The mineral will have been sighted at this time, but was either ignored or misunderstood as copper vitriol .
classification
In the now outdated 8th edition of the systematics of minerals according to Strunz , hydrowoodwardite belongs to the division of " water-containing sulfates with foreign anions ".
The 9th edition of Strunz's mineral systematics, valid since 2001, divides this section more precisely according to the size of the cations involved and the crystal structure, so that the hydrowoodwardite is now in the subdivision of “With only medium-sized cations; Layers of edge-linked octahedra ”. Here it forms together with carboydite , glaucokerinite , honessite , hydrohonessite , motukoreaite , mountkeithit , natroglaukokerinite , nikischerite , shigaite , SO4-hydrotalcite-8.8Å , SO4-hydrotalcite-11Å wermlandite , woodwardite , zinc aluminite and zincowoodwardite group 7.D zincowoodwardite .
The systematics of minerals according to Dana also assigns the mineral to the class of sulfates, but there in the division of " hydrated sulfates with hydroxyl or halogen and the general formula (A + B 2+ ) 6 (XO 4 ) Z q • x ( H 2 O) ”, where it forms the unnamed group 02/31/02 with woodwardite , zincowoodwardite and the polytypes zincowoodwardite-1T and zincowoodwardite-3R .
Crystal structure
Hydrowoodwardite crystallizes trigonal in the space group R 3 m (space group no. 166) with the lattice parameters a = 3.07 Å and c = 31.9 Å as well as 3 formula units per unit cell .
properties
In the air, hydrowoodwardite dehydrates within a few weeks, which means that it loses part of its crystal water and finally changes to woodwardite . The base distance is reduced without intermediate steps from 10.65 Å (hydrowoodwardite) to 8.8 Å (woodwardite), which means that the two minerals can be easily distinguished by radiography.
Education and Locations
Hydrowoodwardite forms in rare cases in oxidized parts of metal sulfide pits. Accompanying minerals include woodwardite , Schulenbergite , Namuwit , Brianyoungite , Langite and Linarite .
So far (status: 2010) hydrowoodwardite has only been found at a few locations worldwide:
- In Germany, the mineral appeared next to its type locality Grube “St. Briccius "still in the pit" St. Christoph ”near Bärenhecke (glassworks), in the“ Father Abraham ”shaft near Lauta , in the“ St. Johannes ”near Wolkenstein and in the“ Yellow Birch ”mine near Beierfeld in Saxony and in the“ Wildermann ” mine near Müsen in North Rhine-Westphalia.
- In Bolivia, hydrowoodwardite was found in the "Pepitos Mine" near Huanuni .
- Finds of the mineral from Greece at the "Hilarion Mine" on the large dump of Kamariza near Aghios Konstantinos and in the "Maria Mine" in the municipality of Agia Varvara (Attica) have been described.
- The mineral had already been known in Caernarfonshire (also Carnarvonshire , Wales ) since 1976 , but was only partially described and not named by nickel.
See also
literature
- Hydrowoodwardite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 66 kB ; accessed on June 28, 2017]).
Web links
Individual evidence
- ↑ a b c d e f g h Thomas Witzke : The discovery of Hydrowoodwardit at www.strahl.org
- ↑ a b c d e Mindat - Hydrowoodwardite (English)
- ^ 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. 403 .