The occurring between aged volcanic rocks, the cavities tend to be full of deposits of secondary minerals launched by percolating h2o. The glass alone sorts threads, fibres, and skinny partitions in between the vesicles. Rhyolite and trachyte pumices are white, andesite pumices often yellow or brown, and pumiceous basalts (such https://edenproductsltd.co.uk/2025/04/17/the-history-of-pumice-stone-from-ancient-civilisations-to-modern-day-uses/