Contribution
The microtexture of analcime phenocrysts in igneous rocks
Putnis, Andrew; Putnis, Christine; Giampaolo, Ciriaco
European Journal of Mineralogy Volume 6 Number 5 (1994), p. 627 - 632
16 références bibliographiques
publié: Sep 23, 1994
manuscrit accepté: May 20, 1994
manuscrit reçu: Mar 14, 1994
DOI: 10.1127/ejm/6/5/0627
Abstract
Abstract Analcime which has formed by ion-exchange processes from leucite has a characteristic microporous texture when observed by scanning electron microscopy (SEM) and is composed of an aggregate of sub-micrometre crystals, whereas analcime crystallised from a fluid phase in hydrothermal veins has a well crystalline structure. SEM observations of analcime phenocrysts on broken surfaces of volcanic igneous rocks from Sardinia show a microtexture very similar to that in analcime known to be ion-exchanged. Analcime phenocrysts from a lamproite from Jumilla, Spain also show a similar porous microtexture as well as direct evidence of leucite to analcime transformation. This suggests strongly that the analcime phenocrysts in the Sardinian igneous rocks are secondary
Mots-clefs
analcime • leucite • zeolite • ion-exchange • SEM