Zanazziite

{{Short description|Complex hydrated phosphate mineral}} {{Cleanup list|date=May 2019}} {{Infobox mineral | name = Zanazziite | category = Phosphate minerals | boxwidth = | boxbgcolor = | image = Zanazziite - Jenipapo, Itinga, Minas Gerais, Brazil.jpg | imagesize = 280px | caption = Brown crystallized zanazziite on the matrix | formula = Ca₂(Mg,Fe)(Mg,Fe,Mn,Al)₄Be₄(OH)₄(PO₄)₆·6H₂O | IMAsymbol = Zan<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}</ref> | molweight = 1,044.11 g/mol | strunz = 8.DA.10 | system = Monoclinic | class = Prismatic (2/m) <br/><small>(same H-M symbol)</small> | symmetry = ''C''2/c | color = Pale to dark olive green | habit = Bladed, columnar, prismatic | twinning = | cleavage = Good on [100], distinct on [010] | fracture = Brittle | tenacity = | mohs = 5 | luster = Vitreous – pearly | polish = | refractive = n_α = 1.606(2) n_β = 1.610 n_γ = 1.620 | opticalprop = Biaxial (+) | birefringence = | dispersion = r < v | pleochroism = | fluorescence= None | absorption = | streak = White | gravity = 2.76 | density = | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = Transparent to translucent | other = | references =<ref>[http://www.mindat.org/min-4385.html Zanazziite: Zanazziite on Mindat.org]</ref><ref>[http://www.webmineral.com/data/Zanazziite.shtml Zanazziite on Webmineral]</ref> }} '''Zanazziite''' is a complex hydrated phosphate mineral from the roscherite group. It is a magnesium beryllium phosphate mineral.<ref name=Atencio>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.</ref> Zanazziite arises as barrel-shaped crystals and can reach up to 4&nbsp;mm. It grows alongside quartz minerals.<ref name=Leavens/> It is found in the crevices of Lavra da Ilha pegmatite, near Taquaral, in northeastern Minas Gerais, Brazil.<ref name=Leavens>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.</ref> Zanazziite is named after Pier F. Zanazzi. Zanazziite has an ideal chemical formula of Ca₂Mg₅Be₄(PO₄)₆(OH)₄·6H₂O.<ref name=Leavens/>

==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.<ref name=Leavens/> In a separate sample, beryllium was 84.93&nbsp;mg by atomic absorption spectrophotometry. To determine water an H analyzer was used on duplicate samples of about 25&nbsp;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.<ref name=Leavens/><ref name=Fanfani>Fanfani, L., Zanazzi, P.F., and Zanzari, A.R. (1977) The crystal structure of roscherite. Tschermaks Min. Petr.Mitt., 22, 266–277.</ref> Zanazziite belongs to the roscherite-group. The roscherite-group nomenclature is based on the dominant cation in the Me-site; valid species include: Roscherite (<chem>Mn^2+</chem>), Zanazziite (<chem>Mg^2+</chem>) and Greifensteinite (<chem>Fe^2+</chem>).<ref name=Leavens/> 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.<ref name=Rast05>Rastsvetaeva, R.K., Chukanov, N.V., and Verin, I.A.(2005) Crystal structure of roscherite. Dok. Akad. Nauk. Russia, 403, 768–771.</ref>

==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).<ref name=Leavens/> X-ray diffraction analyzed cations sharing on octahedral sites. Uncertainty in analyzing zanazziites distribution of cations on M1 and M2 sites.<ref name=Leavens/> The M2 site in zanazziite is indistinct; it contains two Me-O bond distances, and two Me-OH bond distances.<ref name=Fanfani/> 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.<ref name=Rast05/><ref name=Rast09>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.</ref> The biaxial orientation of the extinction angles: <math>X=b; Z^a=3</math> degrees, angles: <math>\alpha=1.606, \beta=1.610, \gamma=1.620</math>, optical axis angle: 2V which was measured = 72 degrees and 2V which was calculated = 65 degrees.<ref name=Leavens/><ref name=Rast05/> 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.<ref name=Leavens/><ref name=Rast05/><ref name=Rast09/>

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.<ref name=Leavens/>

==Physical properties== Zanazziite is usually pale green and occasionally dark green. It is a 5 on the Mohs hardness scale.<ref name=Fanfani/> Optically biaxial +, ex = 1.606, 13 =1.610, "y = 1.620, 2V, = 72°(65° calc) X = b, Z:[100] 3° in obtuse 13; and the density = 2.76 measured, 2.77 calculated. Zanazziite has a vitreous luster, slightly pearly on the cleavage surfaces. Its cleavage is {100} good, {010} distinct. Zanazziite is nonfluorescent in longwave or shortwave ultraviolet light.<ref name=Leavens/> Zanazziite also shares many physical properties with roscherite.

==Geologic occurrence== The roscherite analog zanazziite was found in Lavar da Ilha deposits in Minas Gerais, Brazil.<ref>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.</ref> Zanazziite grows usually along the surface of quartz minerals. It occurs in pegmatite in beds of the Jequitinhonha river valley.<ref name=Leavens/> The pegmatite consists of a wall zone rich in feldspar and muscovite, and a quartz core.<ref name=Leavens/><ref name=Fanfani/> The core margin has small pockets and crevices which contain quartz crystals and a number of phosphate minerals (on which the roscherite minerals accumulate).<ref name=Leavens/> This is special to quartz and phosphate due to the rich locality of Minas Gerais. Minas Gerais contains the world's most diverse concentration of complex granitic pegmatites. This region is responsible for the production of gem beryl, chrysoberyl, topaz, tourmaline, and kunzite.<ref name=Atencio/><ref>Atencio, D., Coutinho, J.M.V., and Menezes Filho, L.A.D.(2005) Roscherite group minerals from Brazil. Mineral records., 4, 1–16.</ref>

==See also== {{Portal|Earth sciences}} *List of minerals *List of minerals named after people

==References== {{Reflist}}

{{Commons category}}

{{Manganese minerals}}

Category:Calcium minerals Category:Magnesium minerals Category:Iron minerals Category:Manganese(II) minerals Category:Aluminium minerals Category:Beryllium minerals Category:Phosphate minerals Category:Monoclinic minerals Category:Minerals in space group 15