The happening amid outdated volcanic rocks, the cavities tend to be crammed with deposits of secondary minerals released by percolating drinking water. The glass alone varieties threads, fibres, and skinny partitions involving the vesicles. Rhyolite and trachyte pumices are white, andesite pumices normally 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/