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Related to trachytic: Perthite, Trachytic Texture


The light-colored, aphanitic rock (the volcanic equivalent of syenite), composed largely of alkali feldspar with minor amounts of mafic minerals.



a cenotypal extrusive, usually porphyritic rock. Porphyritic phenocrysts and microlites embedded in volcanic glass are represented by sanidine; neutral and acid plagioclase, biotite, pyroxene, or amphibole are encountered in lesser amounts. Trachyte is the extrusive equivalent of syenite. It consists of up to 60 percent silica and up to 10 percent alkalies. The rock is rough to the touch. There are glassy trachytes, such as obsidians and pumices, and trachytic tuffs. Trachytes grade into liparites, andesites, and basalts. They are found in the Caucasus and, outside the USSR, in Italy and France. Trachyte is a relatively rare rock. (See also.)

References in periodicals archive ?
This is no fault of the editor, Reinhold Smid, as many who have labored through the laconic and trachytic style of Husserl's research manuscripts would happily confirm.
Other igneous rocks in the vicinity include the rhyolitic intrusions of Carrizo Peak (Pertl, 1984) and the Vera Cruz Mountains to the north of the dike swarm and the predominantly andesitic to trachytic flows, breccias, and agglomerates of the Sierra Blanca volcanic sequence (Thompson, 1966) to the south and west.
The mineral occurrences are hosted by a highly mixed sequence of andesitic to locally trachytic volcanics, volcaniclastic sediments, and minor limestone.
It is dominated by a granodiorite phase and is cross-cut by some later trachytic, doleritic, and lamprophyre dikes.
Fyffe and Barr (1986) examined some of the felsic volcanic rocks in the vicinity of Cumberland Hill, including lava flows and tuffs in a rhyolitic unit and underlying trachytic unit.
Originally described by Blum as synonymous with nepheline syenite, and later applied by Brogger to nepheline syenite with trachytic texture.
The Zubrnice Fault could be important for the development of the CS Volcanic Centre, as the "mondhaldeite" body on this fault limits the crater vent filled with trachytic breccia in the SW.
2000; Weisenberger & Spurgin, 2009) would suggest that Colombia has zeolite deposits; such similarities concern tectonic setting, type of volcanism and deposits and the occurrence of explosive rhyolitic and trachytic volcanic rocks having alkaline to calcoalkaline affinity.
The rock has been variously [TABULAR DATA FOR TABLE 1 OMITTED] described as tinguaite (Clark, 1955; Hodgson, 1969), trachytic phonolite (Hanes, 1962) and nepheline syenite (Currie, 1976; Globensky, 1985).
Modal composition is trachytic (Table 1) while chemical composition of sample PPG-005 suggests high-K cal-alkaline rhyolites (Figure 7).
Slip and normal NW trending faults interact with inverse NE trending regional structures and possibly create the volcanic conduits for trachytic to rhyolitic magmas of alkaline affinity (Cepeda & Pardo, 2004).