Picrite Basalt
“Olivine-loaded eruption from the deep mantle”
Picrite basalt is an olivine-rich variety of basalt containing over 12% magnesium oxide, with abundant olivine phenocrysts giving it a greenish-speckled appearance on dark surfaces. It erupts at unusually high temperatures from deep mantle sources, often associated with mantle plumes.
olivine (phenocrysts), plagioclase, clinopyroxene, chromite, volcanic glass
Kilauea (Hawaii — picritic lavas), West Greenland, Gorgona Island (Colombia), Iceland, Baffin Island (Canada)
5.5-6.5
Picritic eruptions at Kilauea bring up olivine crystals so abundantly that they accumulate on beaches as 'green sand' — Papakōlea Beach on Hawaii's Big Island is one of only four green sand beaches in the world.
Test Your Knowledge
What famous Hawaiian beach feature is created by the olivine crystals in picritic eruptions?
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