CRYSTAL CHEMISTRY OF THE ELBAITE-SCHORL SERIES
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dc.contributor.author | Bosi F. | |
dc.contributor.author | Andreozzi G.B. | |
dc.contributor.author | Federico M. | |
dc.contributor.author | Graziani G. | |
dc.contributor.author | Lucchesi S. | |
dc.date.accessioned | 2023-12-03T03:59:55Z | |
dc.date.available | 2023-12-03T03:59:55Z | |
dc.date.issued | 2005 | |
dc.identifier | https://www.elibrary.ru/item.asp?id=14635641 | |
dc.identifier.citation | American Mineralogist, 2005, 90, 11-12, 1784-1792 | |
dc.identifier.issn | 0003-004X | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/42099 | |
dc.description.abstract | The crystal-chemistry of 13 elbaite-schorl tourmaline crystals from the Cruzeiro pegmatite (Minas Gerais, Brazil) was studied with a multi-analytical approach (SREF, EMPA, SIMS, MS). Effective cation radii at the Y and Z sites and site populations were refined by a minimization procedure. The results indicate that the crystals belong to the alkali group. Elbaite crystals are O2−-free at the W and V sites and show OH content at the O2 site (up to 0.2 apfu). Conversely, schorl crystals always show O2− at the W site. The main substitutional mechanism is the dehydroxylation type: The T site is characterized by TSi → TAl substitution. is linearly correlated with vacancy content in crystals with (OH + F) ≤ 4, whereas it is almost constant in crystals with OH at the O2 position. Along the series, is inversely correlated with YAl. The Z site is almost fully occupied by R3+ (with ZAl largely dominant) and the ZFetot ↔ ZAl substitution explains the inverse correlation of with ZAl. In the elbaite compositional range, lattice parameters are functions of , whereas in the schorl range they are essentially functions of . Along the whole elbaite-schorl series, both chemical substitutions and size increase of Y are far larger than those of Z. In spite of this, lattice parameters increase with as much as with . This is due to the role of the [ZO6] polyhedra, which extend along a and c to form the skeleton of the tourmaline structure. Therefore, any change in the size of Z leads to a change in the whole structure. | |
dc.subject | crystal chemistry | |
dc.subject | elbaite | |
dc.subject | schorl | |
dc.subject | tourmaline | |
dc.title | CRYSTAL CHEMISTRY OF THE ELBAITE-SCHORL SERIES | |
dc.type | Статья | |
dc.identifier.doi | 10.2138/am.2005.1827 |
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