Descripción de la macla de la frondelita-rockbridgeita asociada a las pegmatitas del Macizo de L´Arize, Pirineos (Ariege).
- F. Fontan 1
- E. Roda 2
- 1 Laboratoire de Minéralogie, (U. R. A. 067), Université Paul Sabatier, 39 Allées Jules Guesde, 31000, Toulouse, Francia.
- 2 Dpto. Mineralogía y Petrología, Universidad del País Vasco/EHU, Apdo. 644, 48080 Bilbao.
ISSN: 0213-683X
Année de publication: 1996
Número: 20
Pages: 1524-1526
Type: Article
D'autres publications dans: Geogaceta
Résumé
A cruciform intergrowth in a phosphate of the frondelite-rockbridgeite series associated with beryl-columbite pegmatites is studied on the basis of geometric considerations. The crystallographical calculations prove, for the first time, the existence of a reticular pseudomeroedric twinning in frondelite, having as twin plane the (041), an obliquity of =3 and a twin index =7, which may explain the rarity of this twinning.