The taking place amongst previous volcanic rocks, the cavities usually are filled with deposits of secondary minerals released by percolating h2o. The glass alone varieties threads, fibres, and slim partitions between the vesicles. Rhyolite and trachyte pumices are white, andesite pumices typically 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/