Fosfatos E Silicatos Secundários De Urânio De Perus, São Paulo

Abstract

Secondary uranium phosphates and silicates occur as placoid crystals and crusts, colored green to yellow, filling fractures in the tourmaline-bearing granitic pegmatite of Perus, northwestern part of the city of São Paulo, southeastern Brazil. The following phosphates were identified by X-ray diffractometry, optical properties, EDS and wet chemical analyses: autunite, meta-autunite, meta-torbernite, chernikovite, metauranocircite and phurcalite. Chernikovite is a new mineral name, superseding "hydrogen autunite", whilst meta-uranocircite is described for the first time at Perus. Phurcalite was previously referred as "mineral X from Perus"; a new structural formula [Ca 2 (UO 2) 3 O 2 (PO 4) 2 .7H 2 O] is attributed to this species. Previous literature on Perus also mentions the occurrence of torbernite, bassetite and phosphuranylite, not yet identified by the authors. The presence of the following silicates has been verified: uranophane-alpha, uranophane-beta, haiweeite and barian weeksite. The last mineral, a first quotation for this locality, is the variety with the largest Ba content as yet described. The occurrence of meta-haiweeite needs confirmation. Opal (tridymite and cristobalite), secondary quartz, saponite and rhodochrosite occur associated to the uranium minerals.

The Inventory of Geological Heritage of the State of São Paulo, Brazil: Methodological Basis, Results and Perspectives

“…Another case that can be mentioned is the tourmalinebearing Perus Granite, the only example of an extremely fractionated granite type in the state, composed by pegmatite and aplite alternating banding and rich in incompatible chemical elements (B, Li, U and Rb) and peculiar mineralogy, such as tourmaline, uranium phosphates and silicates (Atencio and Hypolito 1994). These rocks occur as small, decametric to hectometric stocks, and other bodies intruded into Mesoproterozoic metavolcano-sedimentary sequences of the Serra do Itaberaba Group (Azevedo 1994).…”

Raman and infrared spectroscopic studies of phurcalite from Red Canyon, Utah, USA – Implications for the molecular structure

“…Phurcalite was first described at Bergen an der Trieb, Saxony, Germany by Deliens and Piret [7] as Ca 2 (UO 2 ) 3 (PO 4 ) 2 (OH) 4 Á4H 2 O. Piret and Declerq determined crystal structure of phurcalite [8]. Phurcalite was also described at some other localities [9][10][11][12][13][14][15][16][17][18][19]. Redetermination of the crystal structure of phurcalite was carried out by Silva [20], Atencio [21] and Atencio et al [15].…”

Os turmalina granitos de Perus, SP: aspectos geológicos e petrográficos

“…; e.g. Atencio, 1991, para mais detalhes verAtencio, 1988 e Atencio &Hypólito, 1994). A distribuição dos minerais é também bastante inegular, visível principalmente pela concentração das turmalinas, formando manchas irregulares ou faixas de contomos e percursos geralmente irregulares, dentro da massa feldspáticoquartzosa predominante.Rícíes pegmøló¡de ulena.…”