Buchite
“Sediment fused to glass by lava”
Buchite is a rare, partially melted (vitrified) metamorphic rock that forms when extremely hot lava or magma comes into direct contact with clay-rich sediments. The intense heat is enough to partially melt the sediment into a dark, glassy rock, creating a natural example of pyrometamorphism.
glass (vitrified clay), cordierite, mullite, tridymite, relict quartz, magnetite
Isle of Mull (Scotland), Portrush (Northern Ireland), coal fire sites (worldwide), Eifel (Germany), Rotliegend (Germany)
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Similar glassy rocks form naturally where underground coal seams catch fire — some coal fires in Pennsylvania and China have burned for decades, slowly baking surrounding rock into buchite-like material.
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What extreme process creates the vitrified (glassy) texture of buchite?
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