| Full text | |
| Author(s): |
Menezes Filho, Luiz A. D.
[1]
;
Atencio, Daniel
[2]
;
Andrade, Marcelo B.
[3]
;
Downs, Robert T.
[4]
;
Chaves, Mario L. S. C.
[1]
;
Romano, Antonio W.
[1]
;
Scholz, Ricardo
[5]
;
Persiano, Aba I. C.
[6]
Total Authors: 8
|
| Affiliation: | [1] Univ Fed Minas Gerais, Inst Geociencias, BR-31270901 Belo Horizonte, MG - Brazil
[2] Univ Sao Paulo, Inst Geociencias, BR-05508080 Sao Paulo, SP - Brazil
[3] Univ Sao Paulo, Inst Fis Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil
[4] Univ Arizona, Dept Geosci, Tucson, AZ 85721 - USA
[5] Univ Fed Ouro Preto, Escola Minas, Dept Geol, BR-35400000 Ouro Preto, MG - Brazil
[6] Univ Fed Minas Gerais, Inst Ciencias Exatas, Dept Fis, BR-31279901 Belo Horizonte, MG - Brazil
Total Affiliations: 6
|
| Document type: | Journal article |
| Source: | AMERICAN MINERALOGIST; v. 100, n. 2-3, p. 442-446, FEB-MAR 2015. |
| Web of Science Citations: | 8 |
| Abstract | |
Pauloabibite (IMA 2012-090), trigonal NaNbO3, occurs in the Jacupiranga carbonatite, in Cajati County, Sao 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/cm(3). 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 (Na0.88Ca0.04Mn0.022+)Sigma(0.94)(NID0.98Ti0.02)(Sigma 1.00)O-3. X-ray powder-diffraction lines (calculated pattern) {[}d in angstrom(I)(hkl)] are: 5.2066(100)(003), 4.4257(82)(101), 3.9730(45)(012), 2.9809(54) (104), 2.3718(88)(2 (1) over bar3), 1.9865(28)(024), 1.8620(53)(2 (1) over bar6), and 1.5383(30)(300). It is trigonal, space group: R (3) over bar, a = 5.3287(5), c = 15.6197(17) angstrom, Z = 384.10(7) angstrom(3), Z = 6. The crystal structure was solved (R-1 = 0.0285, wR(2) = 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). (AU) | |
| FAPESP's process: | 11/22407-0 - New and rare Brazilian mineral species characterization |
| Grantee: | Daniel Atencio |
| Support Opportunities: | Regular Research Grants |
| FAPESP's process: | 13/03487-8 - Center of characterization of new mineral species: Raman spectroscopy, electron microprobe and X-ray and neutron diffraction |
| Grantee: | Marcelo Barbosa de Andrade |
| Support Opportunities: | Research Grants - Young Investigators Grants |