Abstract
The recent lavas of Etna are tephritic trachybasalts always showing the same mineral composition: olivine phenocrysts; phenocrysts and microlites of strongly zoned calcic plagioclase, slightly titaniferous and aluminous augite, and titanomagnetite; [and] interstitial sanidine and nepheline accompanied by a minimum amount of sodalite. These minerals have been studied by chemical analysis, as well as by optical and x-ray diffraction methods. Analyses of plagioclase, augite, and olivine have again been carried out and compared with those already published. Sanidine, nepheline, and sodalite which, although implicit in the total chemical analysis of the rock, had never been explicitly described, have been identified by selective staining, microchemical tests, and x-ray diffraction. This has been followed by chemical and modal analysis of the most representative lavas. An average type has been defined and its place in the classification of volcanic rocks discussed.
