DOI

The crystal structures of three Li-Al natural tourmalines (elbaites) containing 0.88-1.39 wt % F are refined to R = 0.0294, 0.0308, and 0.0417. It is revealed that the W threefold anion site is split into two sites, namely, the W1 threefold site and W2 ninefold site (W1-W2 ∼ 0.4 Å, Y-W1 ≥ 1.94 Å, Y-W2 ≥ 1.75 Å). The following hypothesis is proposed and justified: the W1 and W2 sites are partially occupied by OH groups and fluorine anions, respectively. The ratio of the [YO4(OH) 2] octahedra to the [YO4(OH)F] octahedra depends on the fluorine content and varies from structure to structure. The fact that the W site is more than 50% occupied by fluorine in the structures of two tourmalines under investigation allows the conclusion that fluor-elbaite with the ideal formula Na(Li1.5Al1.5)Al6(Si6O 18)(BO3)3(OH)3F is a new mineral species and that elbaite can be considered a superspecies.

Язык оригиналаанглийский
Страницы (с-по)907-913
Число страниц7
ЖурналCrystallography Reports
Том50
Номер выпуска6
DOI
СостояниеОпубликовано - 12 дек 2005

    Предметные области Scopus

  • Химия (все)
  • Материаловедение (все)
  • Физика конденсатов

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