Tephrite
Photographed by Michael P. Klimetz
[Grey Tephrite with Glassy White Hexagonal Sodalite Crystals]
Mount Vesuvius
Somma Vesuvius Complex
Naples
Campania
ITALY
Photographed by Michael P. Klimetz
[Grey Tephrite with Glassy White Hexagonal Sodalite Crystals]
Mount Vesuvius
Somma Vesuvius Complex
Naples
Campania
ITALY
Photographed by Michael P. Klimetz
[Dark Reddish-Grey Tephrite with Glassy Black Euhedral Augite Crystals]
Mount Vesuvius
Somma Vesuvius Complex
Naples
Campania
ITALY
Photographed by Michael P. Klimetz
[Dark Reddish-Grey Tephrite with Glassy Black Euhedral Augite Crystals]
Mount Vesuvius
Somma Vesuvius Complex
Naples
Campania
ITALY
Tephrites are extrusive rocks that are essentially composed of calcic plagioclase, clinopyroxene and feldspathoids. Feldspathoids normally comprise in excess of 10% of felsic mineral components. Tephrites differ from basanites in that they do not contain essential olivine. Tephrites also contain minor amounts of alkali feldspar and they thus grade with increasing alkali feldspar content into the Phonolitic Tephrites and Tephritic Phonolites. Both sodium-rich and potassium-rich Tephrites are common. Sodium-rich varieties are known from the Canary islands and Tahiti while potassium-rich varieties are dominant in the Roman magmatic provinces and Vesuvius.
