Contribution
New data on balangeroite and carlosturanite from alpine serpentinites
Belluso, Elena; Ferraris, Giovanni
European Journal of Mineralogy Volume 3 Number 3 (1991), p. 559 - 566
21 références bibliographiques
publié: Jun 5, 1991
manuscrit accepté: Jan 21, 1991
manuscrit reçu: Aug 18, 1990
DOI: 10.1127/ejm/3/3/0559
Abstract
Abstract Systematic sampling of the serpentinites occurring in the Italian Western Alps has led to the discovery of several new localities where the fibrous silicates balangeroite (two sites) and carlosturanite (twentyone sites) are abundantly present. While balangeroite is confined to the Lanzo Massif, carlosturanite is present in all fractured serpentinites of the explored area ; it is absent in the foliated serpentinites. Correlations between the analysed cations show that minor elements represent structural substitutions, except for traces of Na and K which are due to impurities. Intergrowths of fibrous phases (in particular carlosturanite) with chrysotile, diopside, antigorite and olivine, are shown to be oriented associations. The refinement of a neutrondiffraction powder pattern of balangeroite allows the derivation of precise parameters for a monoclinic cell [a = 19.163(2), b = 19.224(2), c = 9.599(3) Å, y = 89.50(1)°]
Mots-clefs
balangeroite • carlosturanite • serpentinites • oriented associations • neutron diffraction