Zanazziite
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Zanazziite | ||
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Specific gravity 2.76 | | |
Optical properties | Biaxial (+) | |
Refractive index | nα = 1.606(2) nβ = 1.610 nγ = 1.620 | |
Dispersion | r < v | |
Ultraviolet fluorescence | None | |
References | [2][3] |
Zanazziite is a complex hydrated
Composition
Zanazziite was recently analyzed with an ARL-SEMQ microprobe; the values were Durango apatite for P, Rockport fayalite for Mn, and Kakanui hornblende for all others.[5] In a separate sample, beryllium was 84.93 mg by atomic absorption spectrophotometry. To determine water an H analyzer was used on duplicate samples of about 25 mg. FeO was determined by titration. The spectroscopic analysis and other microprobes revealed P2O5, 39.27, SiO2 0.36, Al2O3 1.54, Fe2O3 0.76, CaO 10.65, MgO 11.66, FeO 9.63, MnO 1.77, BeO 9.81, H2O 13.32, total of 98.77.[5][6] Zanazziite belongs to the roscherite-group. The roscherite-group nomenclature is based on the dominant cation in the Me-site; valid species include: Roscherite (), Zanazziite () and Greifensteinite ().[5] The chemical relationship among all of the minerals in the roscherite group rely on a common formula (roscherite) Ca2Mn5Be4(PO4)6(OH)4·6H2O, in which the Mn site can be occupied by other cations previously mentioned.[7]
Structure
Zanazziite belongs to the monoclinic space group C2/c. X-ray diffraction showed the strongest lines in Å, with intensities and indices: 9.50 (90) (110), 5.91 (100) (020), 3.16 (70) (330), 3.05 (50) (510), 2.766 (50) (240), 2.682 (40b) (600), 2.208 (40), 1.642 (50b).[5] X-ray diffraction analyzed cations sharing on octahedral sites. Uncertainty in analyzing zanazziites distribution of cations on M1 and M2 sites.[5] The M2 site in zanazziite is indistinct; it contains two Me-O bond distances, and two Me-OH bond distances.[6] The crystal structure and monoclinic symmetry of the cell data edge lengths: a=15.876A, b=11.860A, c=6.607A, and angle: beta=95.49 degrees. The axial ratio of zanazziite is a=1.3391 b=1 and c=0.5571.[7][8] The biaxial orientation of the extinction angles: degrees, angles: , optical axis angle: 2V which was measured = 72 degrees and 2V which was calculated = 65 degrees.[5][7] In X-ray scattering and diffraction models the data presents an approximation of the number of electrons in each atomic site, giving 17.3 e- in the M2 site and 64.8 e- in the M1 site.[5][7][8]
The crystals in Zanazziite are prismatic to bladed, usually rough, barrel-shaped, with indices {100}, {110} and {001}. Cleavages are on {100} good, and {010} distinct.[5]
Physical properties
Zanazziite is usually pale green and occasionally dark green. It is a 5 on the
Geologic occurrence
The roscherite analog zanazziite was found in Lavar da Ilha deposits in Minas Gerais, Brazil.[9] Zanazziite grows usually along the surface of quartz minerals. It occurs in pegmatite in beds of the Jequitinhonha river valley.[5] The pegmatite consists of a wall zone rich in feldspar and muscovite, and a
See also
References
- S2CID 235729616.
- ^ Zanazziite: Zanazziite on Mindat.org
- ^ Zanazziite on Webmineral
- ^ a b Atencio, D., Chukanov, N.V., Coutinho, J.M.V., Menezes Filho, L.A D., Dubinchuk, V.T. and Möckel, S.(2007) Ruifrancoite, a new Fe3+ -dominant monoclinic member of the roscherite group from Galilea, Minas Gerais, Brazil. The Canadian Mineralogist.,45, 1263–1273.
- ^ a b c d e f g h i j k l m n o Leavens, P.B., White, J.S., and Nelen, J.A.(1990) Zanazziite a new mineral from Minas Gerais, Brazil. The Mineralogical record 21, 413–417.
- ^ a b c d Fanfani, L., Zanazzi, P.F., and Zanzari, A.R. (1977) The crystal structure of roscherite. Tschermaks Min. Petr.Mitt., 22, 266–277.
- ^ a b c d Rastsvetaeva, R.K., Chukanov, N.V., and Verin, I.A.(2005) Crystal structure of roscherite. Dok. Akad. Nauk. Russia, 403, 768–771.
- ^ a b Rastsvetaeva, R., Rozenberg, K., Chukanov, N., and Möckel, S.(2009) The crystal structure of an iron-rich variety of zanazziite belonging to heteropolyhedral framework roscherite-group beryllophosphates. MAIK Nauk, 54, 568–571.
- ^ Rastsvetaeva, R.K., Barinova, A.V., Chukanov, N.V., and Pietraszko, A.(2004) Crystal structure of a magnesium-rich triclinic analogue of greifensteinite. Dok. Akad. Nauk. Russia., 398, 492–497.
- ^ Atencio, D., Coutinho, J.M.V., and Menezes Filho, L.A.D.(2005) Roscherite group minerals from Brazil. Mineral records., 4, 1–16.