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 gray lamprophyric rock is rich in phenocrysts and igneous xenoliths, and appears to have a composition similar to that of a trachyte.
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.
ground Oberon NSW (4) trachyte hammer-dressed Kimberley WA (5, 8) basalt flaked, hammer-dressed?
These slabs are formed by hard, often sedimentary rocks; limestone, sandstone, quartzite, and even basalt, andesite, trachyte, rhyolite, and other flows of volcanic rock.
The client geologist had identified the main constituent ore types in the orebody as follows: trachyte porphyry (76%); quartz trachyte porphyry (12%); Precambrian schist (7%); with Cambrian hornfels and quartzite and horublende trachyte porphyry accounting for the remainder.
Geologically, the island is composed of alkaline basalts, pyroclastic rocks, trachyte and hawaiites (Castillo et al.
Post-shield lavas are generally enriched in K-, Na-, and P-bearing minerals such as hawaiite, mugearite, and trachyte (Macdonald et al.
According to the conducted studies, the following volcanic rocks have been observed in this belt: basalt, basaltic andesite, andesite, trachyte, latite, trachyandesite, dacite and rhyodacite ignimbrite and acidic to intermediate tuffs.