Tephriphonolite or tephri-phonolite is a mafic to intermediate extrusive igneous rock in composition between phonotephrite and

phonolite Phonolite is an uncommon extrusive rock, of intermediate chemical composition between felsic and mafic, with texture ranging from aphanitic (fine-grained) to porphyritic (mixed fine- and coarse-grained). Phonolite is a variation of the igneous ...

. It contains 9 to 14%

alkali In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a basic, ionic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a ...

content and 48 to 57% silica content (see

TAS diagram The TAS classification can be used to assign names to many common types of volcanic rocks based upon the relationships between the combined alkali content and the silica content. These chemical parameters are useful, because the relative proportion ...

). Tephriphonolite is roughly equivalent to tephritic phonolite of the QAPF classification. Tephriphonolite has been found, for example, at

Colli Albani The Alban Hills ( it, Colli Albani) are the caldera remains of a quiescent volcanic complex in Italy, located southeast of Rome and about north of Anzio. The high Monte Cavo forms a highly visible peak the centre of the caldera, but the hig ...

volcano in Italy and in the

Asunción Rift The Asunción Rift is a composite graben and rift in eastern Paraguay. The rift is at some localities filled with up to 2500 m of sediments. The rift has a width of 40 to 25 km and can be divided in three segments. The western segment has a NW ...

of Paraguay.

References

{{petrology-stub Volcanic rocks Mafic rocks Intermediate rocks