| Full text | |
| Author(s): Show less - |
Atencio, Daniel
[1]
;
Bastos Neto, Artur C.
[2]
;
Pereira, Vitor P.
[2]
;
Ferron, Jose T. M. M.
[3]
;
Hoshino, M.
[4]
;
Moriyama, T.
[4]
;
Watanabe, Y.
[4]
;
Miyawaki, R.
[5]
;
Coutinho, Jose M. V.
[1]
;
Andrade, Marcelo B.
[6]
;
Domanik, Kenneth
[7]
;
Chukanov, Nikita V.
[8]
;
Momma, K.
[5]
;
Hirano, H.
[4]
;
Tsunematsu, M.
[4]
Total Authors: 15
|
| Affiliation: | [1] Univ Sao Paulo, Inst Geociencias, BR-05508080 Sao Paulo, SP - Brazil
[2] Univ Fed Rio Grande do Sul, Inst Geociencias, BR-91501970 Porto Alegre, RS - Brazil
[3] Univ Fed Rio Grande do Sul, Inst Geociencias, Programa Posgrad Geociencias, BR-91501970 Porto Alegre, RS - Brazil
[4] Natl Inst Adv Ind Sci & Technol, Inst Georesources & Environm, Tsukuba, Ibaraki 3058567 - Japan
[5] Natl Museum Nat & Sci, Dept Geol & Paleontol, Tsukuba, Ibaraki 3050005 - Japan
[6] Univ Sao Paulo, Sao Carlos Inst Phys, BR-13560970 Sao Carlos, SP - Brazil
[7] Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 - USA
[8] Russian Acad Sci, Inst Problems Chem Phys, Chernogolovka 142432, Moscow Region - Russia
Total Affiliations: 8
|
| Document type: | Journal article |
| Source: | MINERALOGICAL MAGAZINE; v. 79, n. 3, p. 767-780, JUN 2015. |
| Web of Science Citations: | 5 |
| Abstract | |
Waimirite-(Y) (IMA 2013-108), orthorhombic YF3, occurs associated with halloysite, in hydrothermal veins (up to 30 mm thick) cross-cutting the albite-enriched facies of the A-type Madeira granite (similar to 1820 Ma), at the Pitinga mine, Presidente Figueiredo Co., Amazonas State, Brazil. Minerals in the granite are `K-feldspar', albite, quartz, riebeckite, `biotite', muscovite, cryolite, zircon, polylithionite, cassiterite, pyrochlore-group minerals, `columbite', thorite, native lead, hematite, galena, fluorite, xenotime-(Y), gagarinite-(Y), fluocerite-(Ce), genthelvite-helvite, topaz, `illite', kaolinite and `chlorite'. The mineral occurs as massive aggregates of platy crystals up to similar to 1 mu m in size. Forms are not determined, but synthetic YF3 displays pinacoids, prisms and bipyramids. Colour: pale pink. Streak: white. Lustre: non-metallic. Transparent to translucent. Density (calc.) = 5.586 g/cm(3) using the empirical formula. Waimirite-(Y) is biaxial, mean n = 1.54-1.56. The chemical composition is (average of 24 wavelength dispersive spectroscopy mode electron microprobe analyses, O calculated for charge balance): F 29.27, Ca 0.83, Y 37.25, La 0.19, Ce 0.30, Pr 0.15, Nd 0.65, Sm 0.74, Gd 1.86, Tb 0.78, Dy 8.06, Ho 1.85, Er 6.38, Tm 1.00, Yb 5.52, Lu 0.65, O (2.05), total (97.53) wt.%. The empirical formula (based on 1 cation) is (Y0.69Dy0.08Er0.06Yb0.05Ca0.03Gd0.02Ho0.02Nd0.01Sm0.01Tb0.01Tm0.01Lu0.01 )(Sigma 1.00){[}F-2.54 square O-0.25(0.21)](Sigma 3.00). Orthorhombic, Pnma, a = 6.386(1), b = 6.877(1), c = 4.401(1) angstrom, V = 193.28(7) angstrom(3), Z = 4 (powder data). Powder X-ray diffraction (XRD) data {[}d in angstrom (I) (hkl)]: 3.707 (26) (011), 3.623 (78) (101), 3.438 (99) (020), 3.205 (100) (111), 2.894 (59) (210), 1.937 (33) (131), 1.916 (24) (301), 1.862 (27) (230). The name is for the Waimiri-Atroari Indian people of Roraima and Amazonas. A second occurrence of waimirite-(Y) is described from the hydrothermally altered quartz-rich microgranite at Jabal Tawlah, Saudi Arabia. Electron microprobe analyses gave the empirical formula (Y0.79Dy0.08Er0.05Gd0.03Ho0.02Tb0.01 Tm0.01Yb0.01)(Sigma 1.00){[}F2.85O0.08 square(0.07)](Sigma 3.00). The crystal structure was determined with a single crystal from Saudi Arabia. Unit-cell parameters refined from single-crystal XRD data are a = 6.38270(12), b = 6.86727(12), c = 4.39168(8) angstrom, V = 192.495(6) angstrom(3), Z = 4. The refinement converged to R-1 = 0.0173 and wR(2) = 0.0388 for 193 independent reflections. Waimirite-(Y) is isomorphous with synthetic SmF3, HoF3 and YbF3. The Y atom forms a 9-coordinated YF9 tricapped trigonal prism in the crystal structure. The substitution of Y for Dy, as well as for other lanthanoids, causes no notable deviations in the crystallographic values, such as unit-cell parameters and interatomic distances, from those of pure YF3. (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 |