Tephrite

 ( Volcanic Rocks ) 

Tephrite is an igneous rock, volcanic (extrusive) rock, with aphanitic to porphyritic texture. Mineral content is usually abundant (leucite or nepheline), plagioclase, and lesser alkali feldspar. (clinopyroxenes) are common accessory minerals. Quartz and olivine are absent. The absence of olivine distinguishes them from the otherwise similar basanite. It's parameters are defined in the QAPF diagram. Occurrences include leucite nepheline tephrite from Hamberg bei Neckarelz near Heidelberg, Germany,. Retrieved 2012-04-11. phonolite-tephrite at Monte Vulture, Basilicata, Italy and basanite–tephrite in Namibia.