Mineralogical dataset of natural zeolites from Lessini Mounts, Northern Italy: Analcime, natrolite, phillipsite and harmotome chemical composition

This dataset article contains mineralogical and chemical data of some natural zeolites such as analcime, natrolite, phillipsite and harmotome. These minerals were found as secondary phases within vesicles and veins in the basaltic rocks of the Lessini Mounts, Northern Italy. Methods for obtaining the datasets include optical microscopy, X-ray diffraction, scanning electron microscopy and electron probe microanalysis. Analcime forms well-developed, transparent to milky crystals with a typical icositetrahedron habit. The average composition of analcime is calculated as Na(13.79)Ca(0.01)K(0.03)Ba(0.03)[Al(14.28)Si(33.82)O(96)] 16H(2)O, with all of the extra-framework sites occupied by sodium. Natrolite usually forms hemispherical aggregates with glassy, colourless to white thin prismatic crystals, which generally radiate from a central point. The average chemical composition of natrolite is Na(14.28)Ca(0.14)K(0.01)[Al(15.60)Si(24.59)O(80)] 16H(2)O. Crystals of phillipsite-harmotome serie occur in a variety of forms and display a highly variable chemical composition, from almost pure compositions to intermediate values. Phillipsite is more common and its average chemical composition is Ca(1.40)Na(0.29)K(1.08)Ba(0.27)[Al(4.68)Si(11.28)O(32)] 12H(2)O, while harmotome is rare and has an average chemical composition of Ca(0.97)Na(0.20)K(0.36)Ba(0.91)[Al(4.60)Si(11.46)O(32)] 12H(2)O. The obtained dataset can be used for various purposes: it can be used by other authors to compare morphological features and chemical compositions of similar zeolites crystals discovered in other parts of the world, it can be compared with those obtained from similar geologic environments encouraging studies on hydrothermal processes, and it could represent the starting point for a potential exploration of zeolites from an industrial point of view.