Phonolite is an uncommon shallow intrusive or extrusive rock, of intermediate chemical composition between felsic and mafic, with texture ranging from aphanitic (fine-grained) to porphyritic (mixed fine- and coarse-grained).

These include intracontinental hotspot volcanism,[2] such as may form above mantle plumes covered by thick continental crust.

Low-degree partial melting of underplates of granitic material in collisional orogenic belts may also produce phonolites.

Mineral assemblages in phonolite occurrences are usually abundant feldspathoids (nepheline, sodalite, hauyne, leucite and analcite) and alkali feldspar (sanidine, anorthoclase or orthoclase), and rare sodic plagioclase.

[5][6] Nepheline syenites and phonolites occur widely distributed throughout the world[7] in Canada, Norway, Greenland, Sweden, the United Kingdom, the Ural Mountains, the Pyrenees, Italy, Eifel and Kaiserstuhl in Germany, Brazil, the Transvaal region, the Magnet Cove igneous complex of Arkansas, the Beemerville Complex of New Jersey,[8] as well as on oceanic islands such as the Canary Islands.

Phonolite tuff was used as a source of flint for adze heads and such by prehistoric people from Hohentwiel and Hegau, Germany.