碱玄岩

right|thumb|Leucite tephrite from Mayen, [[Eifel, Germany]] Tephrite is an igneous, volcanic (extrusive) rock, with aphanitic to porphyritic texture. Mineral content is usually abundant feldspathoids (leucite or nepheline), plagioclase, and lesser alkali feldspar. Pyroxenes (clinopyroxenes) are common accessory minerals. Quartz and olivine are absent. The absence of olivine distinguishes them from the otherwise similar basanite. Its parameters are defined in the QAPF diagram. Occurrences include leucite nepheline tephrite from Hamberg bei Neckarelz near Heidelberg, Germany, phonolite-tephrite