Zanazziite
- IMA 1986-054
Zanazziit 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 Ca2Be4Mg5 [( OH) 4 | ( PO4 ) 6] · 6H2O and usually develops tönnchenförmige, pseudo-hexagonal crystals to about 4 mm in length in hemispherical radiating mineral aggregates from light to dark olive green, greenish yellow, brownish -yellow color with a white stroke color. The surfaces of transparent to translucent crystals show a glass-like luster, whereas cleavage surfaces have pearlescent on.
With a Mohs hardness of 5 Zanazziit belongs to the medium-hard minerals that is similar to the reference mineral apatite can be scratched with a knife still.
Special Features
The ends of the Zanazziitkristalle often have a characteristic mosaic pattern.
Etymology and history
Was first discovered in Zanazziit " Ilha mine field " in Taquaral in the community Itinga in the Brazilian state of Minas Gerais. Analyzed and described the mineral from 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 ( b. 1939 ). The test results and the name chosen in 1986 to test the mineral status at the International Mineralogical Association (IMA ) submitted ( Eingangs-Nr. IMA 1986-054 ) and the status in the same year accepted. The publication of the discovery of new mineral in 1990 in the Mineralogical Record.
Classification
In the now outdated but still in use 8th edition of the mineral classification by Strunz the Zanazziit belonged to the mineral class of " phosphates, arsenates and vanadates " and then to the Department of " water -containing phosphates with foreign anions ", where he along with Bearsit, Glucin, Griffin Enste Init, Moraesit, Roscherit, Uralolith and Weinebeneit formed a distinct group.
The valid since 2001 and used by the IMA 9th edition of the Strunz'schen Mineral classification assigns the Zanazziit " phosphates with other anions, with H2O " into the category of " phosphates, arsenates and vanadates " and then in the Department of. This division, however, is further divided according to the size of the cations involved, so that the mineral is found according to its composition in the subsection " With small (and occasionally larger ) cations " where there along with Atencioit, Footemineit, Griffin Enste Init, Guimarãesit, Roscherit and Ruifrancoit the " Roscheritgruppe " with the system no. 8.DA.10 forms.
The mainly common in English-speaking classification of minerals according to Dana assigns the Zanazziit in the class of " phosphates, arsenates and vanadates " and there in the department of " water -containing phosphates, etc., with hydroxyl or halogen" one. He is also a member of the " Roscheritgruppe " with the system no. Find 42.07.07 and the other members Roscherit, Griffin Enste Init, Atencioit, Guimarãesit, Footemineit and Ruifrancoit within the sub-division of " water -containing phosphates, etc., with hydroxyl or halogen with (AB ) 5 ( XO4 ) 3Zq × x (H2O) ".
Education and Locations
Zanazziit forms in just zoned granite pegmatites usually together with other phosphates such as Eosphorit, Wardit and Whiteit, but also with albite, apatite, muscovite, pyrite and quartz.
Overall, Zanazziit so far (as of 2011) are detected in 13 localities. Apart from its type locality Taquaral these are in Brazil still lying also in the state of Minas Gerais places Jenipapo de Minas, Belo Monte, the " Teixerinha mine" and the Piauí valley in the municipality Itinga and Linópolis and Mendes Pimentel in Docetal.
Other localities lie on Millstaetter Lake Austria and Newry in Oxford County ( Maine) and Groton in Grafton County ( New Hampshire).
Crystal structure
Zanazziit crystallizes in the monoclinic space group C2 / c ( Raumgruppen-Nr. 15) with the lattice parameters a = 15.87 Å; b = 11.85 Å; c = 6.60 Å and 95.3 ° β = 4 and formula units per unit cell.