Hostname: page-component-797576ffbb-xmkxb Total loading time: 0 Render date: 2023-12-10T10:37:26.913Z Has data issue: false Feature Flags: { "corePageComponentGetUserInfoFromSharedSession": true, "coreDisableEcommerce": false, "useRatesEcommerce": true } hasContentIssue false

Tapiaite, Ca5Al2(AsO4)4(OH)4·12H2O, a new mineral from the Jote mine, Tierra Amarilla, Chile

Published online by Cambridge University Press:  02 January 2018

Anthony R. Kampf*
Mineral Sciences Department, Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, CA 90007, USA
Stuart J. Mills
Geosciences, Museum Victoria, GPO Box 666, Melbourne 3001, Victoria, Australia
Barbara P. Nash
Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah 84112, USA
Maurizio Dini
Pasaje San Agustin 4045, La Serena, Chile
Arturo A. Molina Donoso
Los Algarrobos 2986, Iquique, Chile


Tapiaite (IMA2014-024), Ca5Al2(AsO4)4(OH)4·12H2O, is a new mineral from the Jote mine, Tierra Amarilla, Copiapó Province, Atacama, Chile. The mineral is a late-stage, low-temperature, secondary mineral occurring with conichalcite, joteite, mansfieldite, pharmacoalumite, pharmacosiderite and scorodite in narrow seams and vughs in the oxidized upper portion of a hydrothermal sulfide vein hosted by volcanoclastic rocks. Crystals occur as colourless blades, flattened on {101} and elongated and striated along [010], up to ∼0.5 mm long, and exhibiting the forms {101}, {101} and {111}. The blades are commonly intergrown in subparallel bundles and less commonly in sprays. The mineral is transparent and has a white streak and vitreous lustre. The Mohs hardness is estimated to be between 2 and 3, the tenacity is brittle, and the fracture is splintery. It has two perfect cleavages on {101} and {101}. The calculated density based on the empirical formula is 2.681 g cm–3. It is optically biaxial (+) with α = 1.579(1), β = 1.588(1), γ = 1.610(1) (white light), 2Vmeas = 66(2)° and 2Vcalc = 66°. The mineral exhibits no dispersion. The optical orientation is X ≈ [101]; Y = b, Z ≈ [101]. The electron-microprobe analyses (average of five) provided: Na2O 0.09, CaO 24.96, CuO 0.73, Al2O3 10.08, Fe2O3 0.19, As2O5 40.98, Sb2O5 0.09, H2 O 23.46 (structure), total 100.58 wt.%. In terms of the structure, the empirical formula (based on 32 O a.p.f.u.) is (Ca4.83Cu0.102+Na0.03)Σ4.96(Al2.14Fe0.033+)Σ2.17[(As3.875+Sb0.015+)Σ3.88O16][(OH)3.76(H2O)0.24]Σ4(H2O)10·2H2O. The mineral is easily soluble in RT dilute HCl. Tapiaite is monoclinic, P21/n, with unit-cell parameters a = 16.016(1), b = 5.7781(3), c = 16.341(1) Å, β = 116.704(8)°, V = 1350.9(2) Å3 and Z = 2. The eight strongest lines in the powder X-ray diffraction pattern are [dobs Å(I)(hkl)]: 13.91(100)(101), 7.23(17)(200,002), 5.39(22)(110,011), 4.64(33)(112,211,303), 3.952(42)(113,311,213), 3.290(35)(214,412,114,411), 2.823(39)(303,315) and 2.753(15)(513,115,121,511). The structure of tapiaite (R1 = 5.37% for 1733 Fo > 4σF) contains Al(AsO4)(OH)2 chains of octahedra and tetrahedra that are topologically identical to the chain in the structure of linarite. CaO8 polyhedra condense to the chains, forming columns, which are decorated with additional peripheral AsO4 tetrahedra. The CaO8 polyhedra in adjacent columns link to one another by corner-sharing to form thick layers parallel to {101} and the peripheral AsO4 tetrahedra link to CaO6 octahedra in the interlayer region, resulting in a framework structure.

Research Article
Copyright © The Mineralogical Society of Great Britain and Ireland 2015

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)


Blount, A.M. (1974) The crystal structure of crandallite. American Mineralogist, 59, 4147.Google Scholar
Brown, I.D. and Altermatt, D. (1985) Bond-valence parameters from a systematic analysis of the inorganic crystal structure database. Acta Crystallographica, B41, 244247.CrossRefGoogle Scholar
Chopin, C., Brunet, F., Gebert, W., Medenbach, O. and Tillmanns, E. (1993) Bearthite, Ca2Al[PO4]2(OH), a new mineral from high-pressure terranes of the western Alps. Schweizerische Mineralogische und Petrographische Mitteilungen, 73, 19.Google Scholar
Fanfani, L. and Zanazzi, P.F. (1968) The crystal structure of vauquelinite and the relationships to fornacite. Zeitschrift für Kristallographie, 126, 433443.CrossRefGoogle Scholar
Higashi, T. (2001) ABSCOR. Rigaku Corporation, Tokyo. Huminicki, D.M.C. and Hawthorne, F.C. (2002) The crystal chemistry of the phosphate minerals. Pp. 123253. in: Phosphates (M.L. Kohn, J. Rakovan and J.M. Hughes, editors). Reviews in Mineralogy & Geochemistry, 48. Mineralogical Society of America and the Geochemical Society, Chantilly, Virginia, USA.Google Scholar
Kampf, A.R. and Moore, P.B. (1977) Melonjosephite, calcium iron hydroxy phosphate: its crystal structure. American Mineralogist, 62, 6066.Google Scholar
Kampf, A.R., Mills, S.J., Housley, R.M., Rossman, G.R., Nash, B.P., Dini, M. and Jenkins, R.A. (2013) Joteite, Ca2CuAl[AsO4][AsO3(OH)]2(OH)2(H2O)5, a new arsenate with a sheet structure and unconnected acid arsenate groups. Mineralogical Magazine, 77, 28112823.CrossRefGoogle Scholar
Kampf, A.R., Mills, S.J., Nash, B., Dini, M. and Molina Donoso, A.A. (2014) Tapiaite, IMA 2014-024. CNMNC Newsletter No. 21, August 2014, page 800; Mineralogical Magazine, 78, 797804.Google Scholar
Mandarino, J.A. (2007) The Gladstone-Dale compatibility of minerals and its use in selecting mineral species for further study. The Canadian Mineralogist, 45, 3071324.CrossRefGoogle Scholar
Mills, S.J., Birch, W.D., Kampf, A.R., Christy, A.G., Pluth, J.J., Pring, A., Raudsepp, M. and Chen, Y.-S. (2010) Kapundai t e , (Na,Ca) 2Fe3+ 4 (PO4) 4 (OH)3·5H2O, a new phosphate species from Toms quarry, South Australia: description and structural relationship to mé lonjosephite. American Mineralogist, 95, 754760.CrossRefGoogle Scholar
Mills, S.J., Nestola, F., Kahlenberg, V., Christy, A.G., Hejny, C. and Redhammer, G.J. (2013) Looking for jarosite on Mars: The low-temperature crystal structure of jarosite. American Mineralogist, 98, 19661971.CrossRefGoogle Scholar
Parker, R.L., Salas, R.O. and Perez, G.R. (1963) Geologia de los distritos mineros Checo de Cobre Pampa Larga y Cabeza de Vaca. Instituto de Investigaciones Geologicas, 14, 4042.Google Scholar
Pouchou, J.-L. and Pichoir, F. (1991) Quantitative analysis of homogeneous or stratified microvolumes applying the model "PAP". Pp. 3l-75 in: Electron Probe Quantitation (K.F.J. Heinrich and D.E. Newbury, editors). Plenum Press, New York. Schofield, P.F., Wilson, C.C., Knight, K.S. and Kirk, C.A. (2009) Proton location and hydrogen bonding in the hydrous lead copper sulfates linarite, PbCu (SO4)(OH)2, and caledonite, Pb5Cu2(SO4)3 CO3(OH)6. The Canadian Mineralogist, 47, 649662.Google Scholar
Sheldrick, G.M. (2008) A short history of SHELX. Acta Crystallographica, A64, 112122.CrossRefGoogle Scholar
Yang, H., Jenkins, R.A., Downs, R.T., Evans, S.H. and Tait, K.T. (2011) Rruffite, Ca2Cu(AsO4)2·2H2O,a new member of the roselite group, from Tierra Amarilla, Chile. The Canadian Mineralogist, 49, 877884.CrossRefGoogle Scholar
Supplementary material: File

Kampf et al. supplementary material


Download Kampf et al. supplementary material(File)
File 349 KB