Trachyte


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Related to Trachyte: phonolite

trachyte

[′tra‚kīt]
(petrology)
The light-colored, aphanitic rock (the volcanic equivalent of syenite), composed largely of alkali feldspar with minor amounts of mafic minerals.

Trachyte

 

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 ?
The lithology of the Laoling formation ([Pt.sub.1]z) is dolomitic marble, with an average thickness of 467 m, the lithology of the Changbai formation ([T.sub.3]c) is rhyolite and rhyolitic pyroclastic rocks and the average thickness is 1300 m, the lithology of the Junjianshan formation ([Q.sub.1]pj) is basalt and olivine basalt and the average thickness is 189 m, the lithology of the Baitoushan formation ([Q.sub.2]b) is trachyte and tuffaceous trachyte and the average thickness is about 130 m, and the lithology of the Bingchang formation ([Q.sub.4]bc) is alkaline pumice and the average thickness is about 51.5 m (Figure 1).
Granite, basalt, andesite and trachyte are used as coating materials for buildings.
Murazliev's lawyer Vika Kargabaeva reported that at the time of arrest he had been treated with a diagnosis of acute pharyngitis and trachyte. Murzaliev does not receive necessary medicines, complications developed - inflammation of the ear and otitis, said the lawyer.
Even with similar Si[O.sub.2] contents, the syenitic suite has higher Nb/Y than the granitic suite, and the samples plot in the alkalic fields as the intrusive equivalents of volcanic rocks such as trachyte and alkali rhyolite.
The geology of the Texas Davis Mountains AVA is dominated by a large area of older volcanic rocks (rhyolite, trachyte, lava flows) at lower elevations in the north and east, and younger volcanic rocks (trachyte, rhyolite, tuff, latite) at the higher elevations in the central and southwest areas, including Mount Livermore, Black Mountain and surrounding peaks (Fig.
Given the sparsity of evidence, it is not surprising that the so-called constitution stone of Chios has caused so much controversy about its dating, the order of its sides, the quality of its democracy and whether or not the stone really comes from Chios: Meiggs and Lewis (1988: 17) mention that the red trachyte stone on which the constitution is inscribed is not common on Chios but that it is plentiful in nearby Erythrae.
The gray lamprophyric rock is rich in phenocrysts and igneous xenoliths, and appears to have a composition similar to that of a trachyte. These igneous rocks are connected to a significant mass of lamprophyric rocks (not shown on the above-mentioned geologic map) which border the garnet deposit to the north and to the west.
Geologically, the Law is a volcanic plug, formed around 335 million years ago and composed of phonolitic trachyte.
While this service offers the most direct route through Venice and wonderful views of the city, you have to accept the boat's lurching motion and industrial-level shudders as part of the fun Joining the crowds at the city's main harbour, we bounced our wheelie suitcases over the trachyte and sandstone pavements, passing naff restaurants and tacky carnival masks as we passed through the world's most famous piazza - St Mark's Square.
While this service offers the most direct route through Venice and wonderful views of the city, you have to accept the boat's lurching motion and industrial-level shudders as part of the fun Joining the crowds at the city's main harbour, we bounced our suitcases over the trachyte and sandstone pavements, passing naff restaurants, lanky teenagers and tacky carnival masks as we walked through the world's most famous piazza - St Mark's Square.
Most of the tools were made from trachyte, a rock with a much smoother surface than that of other rock types available at Gona.