| Full text | |
| Author(s): |
Atencio, Daniel
;
Andrade, Marcelo B.
;
Bastos Neto, Artur C.
;
Pereira, Vitor P.
Total Authors: 4
|
| Document type: | Journal article |
| Source: | CANADIAN MINERALOGIST; v. 55, n. 1, p. 115-120, JAN 1 2017. |
| Web of Science Citations: | 4 |
| Abstract | |
Ralstonite is renamed hydrokenoralstonite, ideally square 2Al2F6(H2O). ``Atroarite{''} and the ``AHF{''} phase (hydrated aluminum hydroxy-fluoride, a ``ralstonite-like mineral{''}) are also hydrokenoralstonite. The name ralstonite is transferred to the group, where M3+ cations are dominant at the B site, and Al is dominant among them, and F1- is the dominant anion at the X site. Hydrokenoralstonite from the Pitinga mine, Presidente Figueiredo, Amazonas, Brazil, is intimately associated with galena and sphalerite. It forms chemically homogeneous octahedral crystals, from 0.1 to 1 mm in size. The mineral is colorless with white streak, vitreous luster, transparent, density (calc.): 2.554 g/cm(3). Its empirical formula is (square 1.87Na0.12Rb0.01)(Sigma 2.00) (Al1.86Mg0.14)(Sigma 2.00){[}F-3.46(OH)(2.54)](Sigma 6.00)(H2O). The mineral is cubic, Fd (3) over barm (\#227), a 9.8455(7) (A) over circle , V 954.36 (12) (A) over circle (3), Z = 8. Hydrokenoralstonite exhibits ( Al, Mg) cations with octahedral coordination and Na cations located within distorted cubes. Coulsellite, a rhombohedral pyrochlore-supergroup mineral, ideally (Na,Ca)(2)(Mg,Al)(2)F6F, is renamed fluornatrocoulsellite, and the name coulsellite is transferred to the group, where M2+ cations are dominant at the B site, and Mg is dominant among them, and F1- is the dominant anion at the X site. This nomenclature proposal was approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association. (AU) | |
| FAPESP's process: | 14/50819-9 - SoS RARE: multidisciplinary research towards a secure and environmentally sustainable supply of critical rare earth elements (Nd and HREE) |
| Grantee: | Daniel Atencio |
| Support Opportunities: | Research Projects - Thematic 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 |