The happening among the previous volcanic rocks, the cavities are generally crammed with deposits of secondary minerals introduced by percolating water. The glass by itself varieties threads, fibres, and thin partitions concerning the vesicles. Rhyolite and trachyte pumices are white, andesite pumices frequently yellow or brown, and pumiceous basalts (for https://edenproductsltd.co.uk/2025/04/17/the-history-of-pumice-stone-from-ancient-civilisations-to-modern-day-uses/