Igneous, volcanic rock
Leucite tephrite from Mayen, Eifel , GermanyTephrite 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 . It's parameters are defined in the QAPF diagram. Occurrences include leucite nepheline tephrite from Hamberg bei Neckarelz near Heidelberg , Germany ,[ 1] Monte Vulture , Basilicata , Italy and basanite –tephrite intrusions in Namibia .
References
^ Frenzel, Gerhard (1953). "Die Erzparagenese des Katzenbuckels im Odenwald". Contributions to Mineralogy and Petrology (in German). 3 (6): 409– 444. doi :10.1007/BF01129196 .
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