The [9]-coordinated X site in the crystal structure of tourmaline-group minerals

Autor(en)

Andreas Ertl, Ekkehart Tillmanns

Abstrakt

The [9]-coordinated X site in tourmaline is usually occupied by Na, Ca, K, or is vacant. In contrast to earlier statements in the literature our recent evaluation of 81 tourmaline samples with Al on the Z site has clearly shown that the distance, as could have been expected, is pos. correlated to the av. effective ionic radius of the X-site occupants (r = 0.98 for 81 tourmaline samples, with Al6 at the Z site and (OH)3 at the V site). Olenite and "oxy-rossmanite" samples, in which the V site is not completely occupied by OH, show a significant deviation to this correlation. X-site vacancies (up to ~0.7 apfu), as well as a significant variation of and distances, do not seem to have a significant effect on the distance. Tourmalines of the elbaite-olenite-rossmanite series (with Al6 at the Z site) show a pos. correlation between the and the distance (r = 0.80; 40 samples) due to inductive effects in the structure.

Organisation(en)

Institut für Mineralogie und Kristallographie

Journal

Zeitschrift für Kristallographie - Crystalline Materials

Band

227

Seiten

456-459

Anzahl der Seiten

4

ISSN

2194-4946

Publikationsdatum

2012

Peer-reviewed

Ja

ÖFOS 2012

105113 Kristallographie, 105116 Mineralogie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/4a1a93aa-89ee-44f5-965a-13fd716c0f7b