Pauloabibite, trigonal NaNbO3, isostructural with ilmenite, from the Jacupiranga carbonatite, Cajati, São Paulo, Brazil

Luiz A.D. Menezes Filho, Daniel Atencio, Marcelo B. Andrade, Robert T. Downs, Mário L.S.C. Chaves, Antônio W. Romano, Ricardo Scholz, Aba I.C. Persiano

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10 Scopus citations


Pauloabibite (IMA 2012-090), trigonal NaNbO3, occurs in the Jacupiranga carbonatite, in Cajati County, São Paulo State, Brazil, associated with dolomite, calcite, magnetite, phlogopite, pyrite, pyrrhotite, ancylite-(Ce), tochilinite, fluorapatite, "pyrochlore", vigezzite, and strontianite. Pauloabibite occurs as encrustations of platy crystals, up to 2 mm in size, partially intergrown with an unidentified Ca-Nb-oxide, embedded in dolomite crystals, which in this zone of the mine can reach centimeter sizes. Cleavage is perfect on {001}. Pauloabibite is transparent and displays a sub-Adamantine luster; it is pinkish brown and the streak is white. The calculated density is 4.246 g/cm3. The mineral is uniaxial; n(mean)calc is 2.078. Chemical composition (n = 17, WDS, wt%) is: Na2O 16.36, MgO 0.04, CaO 1.36, MnO 0.82, FeO 0.11, SrO 0.02, BaO 0.16, SiO2 0.03, TiO2 0.86, Nb2O5 78.66, Ta2O5 0.34, total 98.76. The empirical formula is (Na0.88Ca0.04Mn2+0.02)SΣ0.94(Nb0.98Ti0.02)Σ1.00-O3. X-ray powder-diffraction lines (calculated pattern) [d in Å(I)(hkl)] are: 5.2066(100)(003), 4.4257(82)(101), 3.9730(45)(012), 2.9809(54) (104), 2.3718(88)(21"3), 1.9865(28)(024), 1.8620(53)(21"6), and 1.5383(30)(300). It is trigonal, space group: R3", a = 5.3287(5), c = 15.6197(17) Å, V = 384.10(7) Å3, Z = 6. The crystal structure was solved (R1 = 0.0285, wR2 = 0.0636 for 309 observed reflections). Pauloabibite is isostructural with ilmenite and is polymorphic with isolueshite (cubic) and lueshite (orthorhombic). The name is in honor of Paulo Abib Andery (1922-1976).

Original languageEnglish (US)
Pages (from-to)442-446
Number of pages5
JournalAmerican Mineralogist
Issue number2-3
StatePublished - Feb 1 2015


  • Brazil
  • Cajati
  • Jacupiranga mine
  • Pauloabibite
  • carbonatite
  • chemical composition
  • crystal structure
  • ilmenite structure
  • new mineral

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology


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