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, natro- lite, phillipsite and harmotome. These minerals were found as secondary phases within vesicles and veins in the basaltic rocks of the Lessini Mounts, Northern Italy. Meth- ods for obtaining the datasets include optical microscopy, X-ray diffraction, scanning electron microscopy and elec- tron probe microanalysis. Analcime forms well-developed, transparent to milky crystals with a typical icositetrahe- dron habit. The average composition of analcime is calcu- lated 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. Na- trolite usually forms hemispherical aggregates with glassy, colourless to white thin prismatic crystals, which generally radiate from a central point. The average chemical compo- sition 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 composi- tion, from almost pure compositions to intermediate values. Phillipsite is more common and its average chemical com- position 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 chem- ical compositions of similar zeolites crystals discovered in other parts of the world, it can be compared with those ob- tained from similar geologic environments encouraging stud- ies on hydrothermal processes, and it could represent the starting point for a potential exploration of zeolites from an industrial point of view.