| Texto completo | |
| Autor(es): |
Atencio, Daniel
Número total de Autores: 1
|
| Tipo de documento: | Artigo Científico |
| Fonte: | MINERALOGICAL MAGAZINE; v. 87, n. 5, p. 3-pg., 2023-09-01. |
| Resumo | |
Minasgeraisite-(Y) is discredited on the basis of it being an ordered intermediate between datolite and hingganite-(Y) (IMA-CNMNC Proposal 23-F). An idealised formula is (Ca2Y2)2(Be2B2)Si4O16(OH)4, which corresponds to Ca2B2Si2O8(OH)2 (datolite) + Y2Be2Si2O8(OH)2 (hingganite-(Y)). The type material is rich in Bi, the Bi-richest portion yet discovered from the type locality is shown to be an intermediate member between datolite, hingganite-(Y) and a hypothetical end-member phase yet to be found of composition Bi2Be2Si2O8(OH)2. Minasgeraisite-(Y) has a different space group to datolite and hingganite-(Y). This lowering of symmetry to an acentric triclinic system is caused by different element occupancies on the A site of the gadolinite supergroup structure, which for minasgeraisite-(Y) becomes four individual sites. Such an order-disorder of elements is not considered as species-defining criteria despite the change in space group. Therefore, minasgeraisite-(Y) is discredited. (AU) | |
| Processo FAPESP: | 19/23498-0 - Mineralogia brasileira: caracterização de espécies minerais novas e raras |
| Beneficiário: | Daniel Atencio |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |