THE PYROCHLORE SUPERGROUP OF MINERALS: NOMENCLATURE

Autor(es)

Atencio, Daniel ^[1] ; Andrade, Marcelo B. ^[2] ; Christy, Andrew G. ^[3] ; Giere, Reto ^[4] ; Kartashov, Pavel M. ^[5]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Geociencias, BR-05508080 Sao Paulo - Brazil

^[2] Univ Sao Paulo, Inst Fis Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil

^[3] Australian Natl Univ, Res Sch Earth Sci, Canberra, ACT 0200 - Australia

^[4] Univ Freiburg, Inst Geowissensch, D-79104 Freiburg - Germany

^[5] Russian Acad Sci, Inst Geol Ore Deposits Petrog Mineral & Geochem I, Moscow 109017 - Russia

• Tipo de documento: Artigo Científico
• Fonte: CANADIAN MINERALOGIST; v. 48, n. 3, p. 673-698, JUN 2010.
• Citações Web of Science: 130

Resumo

A new scheme of nomenclature for the pyrochlore supergroup, approved by the CNMNC-IMA, is based on the ions at the A, B and Y sites. What has been referred to until now as the pyrochlore group should be referred to as the pyrochlore supergroup, and the subgroups should be changed to groups. Five groups are recommended, based on the atomic proportions of the B atoms Nb, Ta, Sb, Ti, and W. The recommended groups are pyrochlore, microlite, romite, betafite, and elsmoreite, respectively. The new names are composed of two prefixes and one root name (identical to the name of the group). The first prefix refers to the dominant anion (or cation) of the dominant valence {[}or H(2)O or rectangle] at the Y site. The second prefix refers to the dominant cation of the dominant valence {[}or H(2)O or rectangle] at the A site. The prefix `` keno-{''} represents `` vacancy{''}. Where the first and second prefixes are equal, then only one prefix is applied. Complete descriptions are missing for the majority of the pyrochlore-supergroup species. Only seven names refer to valid species on the grounds of their complete descriptions: oxycalciopyrochlore, hydropyrochlore, hydroxykenomicrolite, oxystannomicrolite, oxystibiomicrolite, hydroxycalcioromite, and hydrokenoelsmoreite. Fluornatromicrolite is an IMA-approved mineral, but the complete description has not yet been published. The following 20 names refer to minerals that need to be completely described in order to be approved as valid species: hydroxycalciopyrochlore, fluornatropyrochlore, fluorcalciopyrochlore, fluorstrontiopyrochlore, fluorkenopyrochlore, oxynatropyrochlore, oxyplumbopyrochlore, oxyyttropyrochlore-(Y), kenoplumbopyrochlore, fluorcalciomicrolite, oxycalciomicrolite, kenoplumbomicrolite, hydromicrolite, hydrokenomicrolite, oxycalciobetafite, oxyuranobetafite, fluornatroromite, fluorcalcioromte, oxycalcioromite, and oxyplumboromite. For these, there are only chemical or crystalstructure data. Type specimens need to be defined. Potential candidates for several other species exist, but are not sufficiently well characterized to grant them any official status. Ancient chemical data refer to wet-chemical analyses and commonly represent a mixture of minerals. These data were not used here. All data used represent results of electron-microprobe analyses or were obtained by crystal-structure refinement. We also verified the scarcity of crystal-chemical data in the literature. There are crystalstructure determinations published for only nine pyrochlore-supergroup minerals: hydropyrochlore, hydroxykenomicrolite, hydroxycalcioromite, hydrokenoelsmoreite, hydroxycalciopyrochlore, fluorcalciopyrochlore, kenoplumbomicrolite, oxycalciobetafite, and fluornatroromite. The following mineral names are now discarded: alumotungstite, bariomicrolite, bariopyrochlore, bindheimite, bismutomicrolite, bismutopyrochlore, bismutostibiconite, calciobetafite, ceriopyrochlore-(Ce), cesstibtantite, ferritungstite, jixianite, kalipyrochlore, monimolite, natrobistantite, partzite, plumbobetafite, plumbomicrolite, plumbopyrochlore, stannomicrolite, stetefeldtite, stibiconite, stibiobetafite, stibiomicrolite, strontiopyrochlore, uranmicrolite, uranpyrochlore, yttrobetafite-(Y), and yttropyrochlore-(Y). (AU)

• Processo FAPESP: 09/09125-5 - Minerais novos do Brasil: caracterização cristaloquímica e síntese
• Beneficiário: Daniel Atencio
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 08/04984-7 - Determinação e refinamento da estrutura cristalina de minerais do grupo de pirocloro
• Beneficiário: Marcelo Barbosa de Andrade
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado