Vitrophyre

VITROPHYRE (from the Latin word "vitrum", which means "glass", and Greek word "porphyra", which means "purple, dark red colour" * EN: glass-porphyry, vitrophyre; DE: Vitrophyr; FR: vitrophyre; ES: vitrofiro; RU: витрофир) is the collective name for the effused glassy rocks. Usually vitrophyre is the quartz porphyry, or the orthoclase porphyry, with the glassy (so-called vitrophyric) major mass. They sometimes use vitrophyre as the active mineral additive for the cements.