Tephrite
“Ash-gray alkaline lava”
Tephrite is a dark, fine-grained volcanic rock lacking olivine but rich in clinopyroxene and plagioclase, with nepheline or leucite filling in for the absent quartz. It erupts from moderately alkaline magmas and is common around volcanic centers in continental rift settings and ocean islands.
plagioclase, clinopyroxene (augite), nepheline or leucite, magnetite, apatite
Vesuvius (Italy), Eifel (Germany), Canary Islands, East African Rift, Auvergne (France)
5-6
Some of the lavas that buried Pompeii and Herculaneum in 79 AD were tephrites — the name itself comes from the Greek 'tephra' meaning ash, reflecting its volcanic origin.
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