The developing amongst previous volcanic rocks, the cavities are usually crammed with deposits of secondary minerals released by percolating drinking water. The glass itself sorts threads, fibres, and slender partitions concerning the vesicles. Rhyolite and trachyte pumices are white, andesite pumices frequently yellow or brown, and pumiceous basalts (which include https://edenproductsltd.co.uk/2025/04/17/the-history-of-pumice-stone-from-ancient-civilisations-to-modern-day-uses/