On the presence of leucite in basaltic rocks from central France

The existence of interstitial leucite is demonstrated in a number of alkali-basalts and basanites from the tertiary and quaternary volcanic province of central France. This leucite occurs in nepheline-normative, K₂O-rich basaltic rocks. Available experimental data show that the assemblage nepheline_ss+leucite_ss+ alkali feldspar_ss would be a frequent one, and our observations tend to support the view that it is indeed common in basaltic rocks of appropriate composition.