Zincowoodwardite
| Zincowoodwardite | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 1998-026 |
| chemical formula |
|
|
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) 31.02.02.03 |
| Crystallographic Data | |
| Crystal system | trigonal |
| Crystal class ; symbol | Zincowoodwardite-1T: trigonal-pyramidal Zincowoodwardite-3R: trigonal-rhombohedral |
| Space group | see crystal structure |
| Lattice parameters | see crystal structure |
| Formula units | see crystal structure |
| Physical Properties | |
| Mohs hardness | 1 |
| Density (g / cm 3 ) | measured: 2.66; calculated: 2.71 |
| Cleavage | Please complete |
| colour | greenish blue, light blue to white |
| Line color | Light Blue |
| transparency | translucent |
| shine | Wax gloss |
Zincowoodwardite is a very rarely occurring mineral from the mineral class of "sulfates (and related)" (see classification ) with the chemical composition (Zn 1-x Al x ) (SO 4 ) x / 2 (OH) 2 · nH 2 O ( x <0.5, n <3x / 2) and thus represents the zinc analogue of Woodwardite .
Zincowoodwardite crystallizes polytypically in the trigonal crystal system as zincowoodwardite-1T and in rhombohedral centering as zincowoodwardite-3R . Similar to its relative woodwardite, it develops fibrous crystals up to about 1.5 mm in size and partly pseudo-hexagonal habit , which are arranged in radial to cluster-like aggregates or form crusty coatings. The crystals and aggregates are translucent greenish blue or light blue to white in color and have a wax-like sheen on the surfaces . Zincowoodwardit leaves a light blue line on the marking board .
Like the reference mineral talc, Zincowoodwardite has the lowest possible Mohs hardness of 1, i.e. H. their surfaces can be scraped off with a fingernail.
Etymology and history
Zincowoodwardite was first found in 1998 in the "Christiana Mine" and "Hilarion Mine" near Agios Konstantinos (Kamariza) in Attica , Greece. The mineral was analyzed and described by Thomas Witzke and Gunnar Raade , who named it because of its close relationship to woodwardite and its composition with a predominance of zinc. Zincowoodwardite was recognized as an independent mineral by the International Mineralogical Association (IMA) in the same year under the number IMA1998-026 . The research results and the recognized name were published two years later in the New Yearbook for Mineralogy under the title Zincowoodwardite, a new mineral of the hydrotalcite group .
Type material of the mineral is in the mineralogical collection of the Technical University Bergakademie Freiberg .
classification
In the now outdated, but still in use 8th edition of the systematics of minerals according to Strunz , the zinc owdwardite belonged to the mineral class of "sulfates, selenates, tellurates, chromates, molybdates, wolframates" and there to the department of "hydrous sulfates with foreign anions ", where he together with Bechererite , Camérolait , carbonate Cyanotrichit , Carrboydit , Chalkoalumit , Cyanotrichit , Glaukokerinit , Hydrombobomkulit , Hydrowoodwardit , Kirgizstanit , Mbobomkulit , Nickelalumit , Spangolith , Woodwardite and Zinkaluminit the unnamed group VI / D.08 formed.
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns Zincowoodwardite to the class of "sulfates (selenates, tellurates, chromates, molybdates and tungstates)" and there in the department of "Sulphates (selenates, etc.) with additional anions, with H 2 O". However, this section is further subdivided according to the relative size of the cations involved and the crystal structure, so that the mineral is classified in the sub-section “With only medium-sized cations; Layers of edge-sharing octahedra "can be found, where together with carboydite, glaucokerinite, honessite , hydrohonessite , hydrowoodwardite, motukoreaite , mountkeithit , natroglaucokerinite , nikischerite , shigaite , vermlandite , woodwardite and zinc aluminite with the" woodwardite group ". 7.DD.35 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns zincowoodwardite to the class of "sulfates, chromates and molybdates" and there to the category of "water-containing sulfates with hydroxyl or halogen". Here it is together with Woodwardit, Hydrowoodwardit, Zincowoodwardit-1T and Zincowoodwardit-3R in the "Woodwardit group" with the system no. 02/31/02 within the subdivision of " Water-containing sulphates with hydroxyl or halogen with (A + B 2+ ) 6 (XO 4 ) Z q × x (H 2 O) ".
Crystal structure
Zincowoodwardit crystallizes polytype, that is, it forms alternating layers with trigonal-primitive and trigonal-rhombohedral symmetry, which are called "Zincowoodwardit-1T" and "Zincowoodwardit-3R". The structure is closely related to that of the hydrotalcite .
- Zincowoodwardite-1T crystallizes trigonally in the space group P 3 (space group number 147) with the lattice parameters a = 3.063 Å and c = 8.91 Å as well as one formula unit per unit cell .
- Zincowoodwardite-3R crystallizes rhombohedral in the space group R 3 m with the lattice parameters a = 3.065 Å and c = 25.42 Å as well as three formula units per unit cell .
Education and Locations
Zincowoodwardite is formed in the oxidation zone of zinc- bearing deposits and in old mine workings by precipitation from water under neutral to slightly basic conditions. Here, Zincowoodwardite occurs in paragenesis with glaucocerinite , hemimorphite , natroglaucocerinite , serpierite and / or zaccagnaite, depending on where it was found.
In addition to its type locality "Christiana Mine" and "Hilarion Mine" near Aghios Konstantinos, Zincowoodwardite was found in Greece in the "Serpieri Mine" (also Aghios Konstantinos) and in the "Maria Mine" at Cape Sounion . Other sites are the Friedrichssegen mine in the municipality of Frücht (Rhineland-Palatinate) in Germany and “Le Penay” near La Léchère in the French province of Tarentaise .
See also
literature
- Thomas Witzke , Gunnar Raade : Zincowoodwardite, [Zn1-x Alx (OH) 2] [(SO4) x / 2 (H2O) n], a new mineral of the hydrotalcite group . In: New yearbook for mineralogy / monthly books . tape 10 , 2000, ISSN 0028-3649 , p. 455-465 .
Web links
- Mineral Atlas: Zincowoodwardit , Mineralienatlas: Zincowoodwardit-1T and Mineralienatlas: Zincowoodwardit-3R (Wiki)
Individual evidence
- ↑ a b IMA / CNMNC List of Mineral Names; May 2017 ( Memento of July 21, 2017 in the Internet Archive ) (English, PDF 1.8 MB; p. 206)
- ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 6th completely revised and supplemented edition. Weise, Munich 2014, ISBN 978-3-921656-80-8 .
- ↑ Type mineral catalog of the University of Hamburg: Zincowoodwardit
- ↑ a b American Mineralogist Crystal Structure Database - Zincowoodwardite (English, 2000)
- ↑ a b Thomas Witzke : First descriptions of new minerals in which I am involved
- ↑ Mineralogical Association of Canada - data sheet from Zincowoodwardite ( Memento from November 25, 2015 in the Internet Archive ) (English, PDF 24.5 kB)
- ↑ Find location list for Zincowoodwardite at the Mineralienatlas and at Mindat - Zincowoodwardite