santorinite

santorinite

[san′tȯr·ə‚nīt]
(petrology)
A light-colored extrusive rock containing approximately 60-65% silica and calcic plagioclase (labradorite to anorthite) as the only feldspar.
A hypersthene andesite containing plagioclase crystals that have labradorite cores and sodic rims and a groundmass with microlites of sodic oligoclase.