The rhyolite complex capping the Kishegy volcanic massif was formed during the Miocene volcanism of the Matra mountain region. It contains pumice (at least 27 meters in thickness) and bands of perlite in the basal portion, overlain by spherulitic, lithophysae, and felsitic types of rhyolite. The different varieties of vitric and felsitic rocks reflect an inhomogeneous distribution of water vapor in the lava, and perhaps local variations in the rate of cooling and consolidation, rather than any fundamental differences in chemical composition. The lithophysae and felsitic rhyolites have been quarried since the Middle Ages for building stone; the perlite and pumice have possible applications in the modern building industry.

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