Phonolite

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Related to phonolitic: nephelinite, Tephrite, trachybasalt

phonolite

[′fō·nə‚līt]
(petrology)
A light-colored, aphanitic rock of volcanic origin, composed largely of alkali feldspar, feldspathoids, and smaller amounts of mafic minerals.

Phonolite

 

(from the Greek phone,”sound,” and lithos,”stone”), the extrusive equivalent of nepheline syenite. Phonolite consists of feldspathoids (nepheline and other rocks), sanidine, and chromatic minerals (alkaline pyroxene and amphibole). It often contains phenocrysts of hauynite, noselite, and, sometimes, plagioclase. Its texture is usually porphyritic. The cleavage is laminar; individual plates of phonolite ring strongly when struck with a hammer (hence the name). Phonolite is used as gravel in road paving and as an aggregate for concrete.

References in periodicals archive ?
Paleoweathering profiles on syenitic and phonolitic bedrocks are widerspread not only in the present-day tropical and subtropical terrains (Brazil: Valeton et al., 1991; Schumann, 1993; Boulange and Colin, 1994; Cameroon: Bilong, 1988; Braun et al., 1990; Ivory Coast: Boulange et al., 1975), but also in some places within the Ohre/Eger Rift, NW Bohemia.
Calcite and dolomite were dissolved in places, and analcime, sodalite, nepheline, and feldspars in the phonolitic host rocks were locally altered to clay.