Zanazziit
| Zanazziit | |
|---|---|
 (field of view: 9 mm) |
|
| General and classification | |
| other names |
IMA 1986-054 |
| chemical formula | Ca 2 Be 4 Mg 5 [(OH) 4 | (PO 4 ) 6 ] • 6H 2 O |
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.DA.10 ( 8th edition : VII / D.01) July 42, 07.03 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Room group (no.) | C 2 / c (No. 15) |
| Lattice parameters |
a = 15.87 Å ; b = 11.85 Å; c = 6.60 Å β = 95.3 ° |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | 5 |
| Density (g / cm 3 ) | measured: 2.76; calculated: 2.77 |
| Cleavage | good after {100}, clearly after {010} |
| colour | light to dark olive green, greenish yellow, brownish yellow |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass luster, pearlescent luster on cleavage surfaces |
| Crystal optics | |
| Refractive indices |
n α = 1.606 (2) n β = 1.610 n γ = 1.620 |
| Birefringence | δ = 0.014 |
| Optical character | biaxial positive |
| Axis angle | 2V = measured: 72 °; calculated: 66 ° |
Zanazziite is a rarely occurring mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the monoclinic crystal system with the chemical composition Ca 2 Be 4 Mg 5 [(OH) 4 | (PO 4 ) 6 ] · 6H 2 O and develops mostly barrel-shaped, pseudo-hexagonal crystals up to about 4 mm in length in hemispherical, radiating mineral aggregates from light to dark olive green, greenish yellow, brownish yellow color with white streak color . The surfaces of the transparent to translucent crystals have a glass-like sheen , whereas the cleavage surfaces have a pearlescent sheen .
With a Mohs hardness of 5, zanazziite is one of the medium-hard minerals that, like the reference mineral apatite, can still be scratched with a knife.
Special properties
The ends of the zanazziite crystals often have a characteristic, mosaic-like pattern.
Etymology and history
Zanazziit was first discovered in the "Ilha Grubenfeld" near Taquaral in the municipality of Itinga in the Brazilian state of Minas Gerais . The mineral was analyzed and described by Peter B. Leavens, John Sampson White and Joseph A. Nelen, who named it after the Italian professor of mineralogy at the University of Perugia Pier F. Zanazzi (* 1939). The test results and the chosen name were submitted to the International Mineralogical Association (IMA) for examination of the mineral status in 1986 (accession no. IMA 1986-054 ) and the status was recognized that same year. The publication of the discovery of the new mineral took place in 1990 in the Mineralogical Record .
classification
In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the zanazziite belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "water-containing phosphates with foreign anions ", where it belongs together with bearsite , glucin and greifensteinite , Moraesite , Roscherite , Uralolith and Weinebeneit formed a separate group.
The 9th edition of Strunz's mineral systematics, which has been valid since 2001 and is used by the IMA, assigns the zanazziit to the class of “phosphates, arsenates and vanadates” and there to the category of “phosphates etc. with additional anions; with H 2 O “. However, this section is further subdivided according to the size of the cations involved , so that the mineral can be found according to its composition in the sub-section “With small (and occasionally larger) cations”, where it is found together with Atencioite , Footemineite , Greifensteinite, Guimarãesit , Roscherite and Ruifrancoit the "Roscherite group" with the system no. 8.DA.10 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns zanazziit to the class of "phosphates, arsenates and vanadates" and there to the category of "water-containing phosphates, etc., with hydroxyl or halogen". Here he is also a member of the "Roscherite group" with the system no. July 42, 2007 and the other members Roscherit, Greifensteinit, Atencioit, Guimarãesit, Footemineit and Ruifrancoit within the subdivision of "Hydrous phosphates etc., with hydroxyl or halogen with (AB) 5 (XO 4 ) 3 Z q × x (H 2 O ) ”.
Education and Locations
Zanazziite forms in simply zoned granite - pegmatites mostly together with other phosphates such as eosphorite , wardite and whiteit , but also with albite , apatite , muscovite , pyrite and quartz .
In total, Zanazziit has so far (as of 2011) been detected at 13 sites. In addition to its type locality Taquaral, these are the places Jenipapo de Minas , Monte Belo , the "Teixerinha mine" and the Piauí valley in the municipality of Itinga as well as Linópolis and Mendes Pimentel in the Docetal , which are also in the state of Minas Gerais .
Other locations are on Lake Millstatt in Austria as well as Newry in Oxford County (Maine) and Groton in Grafton County (New Hampshire).
Crystal structure
Zanazziit crystallizes monoclinically in the space group C 2 / c (space group no. 15) with the lattice parameters a = 15.87 Å ; b = 11.85 Å; c = 6.60 Å and β = 95.3 ° as well as 4 formula units per unit cell .
See also
Individual evidence
- ↑ a b IMA / CNMNC List of Mineral Names - Zanazziite (English, PDF 1.8 MB)
- ↑ Webmineral - Zanazziit (English)
- ^ A b c 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. 493 .
- ↑ Zanazziite , in: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 65.9 kB )
- ↑ a b c Mindat - Zanazziite (English)
literature
- Peter B. Leavens, John Sampson White, Joseph A. Nelen: ZANAZZIITE A NEW MINERAL FROM MINAS GERAIS, BRAZIL , in: The Mineralogical Record , 21, pp. 413–417 (English, PDF 4 MB)
Web links
- Mineral Atlas: Zanazziit (Wiki)