The taking place amongst old volcanic rocks, the cavities are usually stuffed with deposits of secondary minerals released by percolating h2o. The glass alone varieties threads, fibres, and slim partitions in between the vesicles. Rhyolite and trachyte pumices are white, andesite pumices frequently yellow or brown, and pumiceous basalts (which https://edenproductsltd.co.uk/2025/04/17/the-history-of-pumice-stone-from-ancient-civilisations-to-modern-day-uses/