Rhyolite


Rhyolite

"This page is about a volcanic rock. For the ghost town see Rhyolite, Nevada, and for the satellite system, see Rhyolite/Aquacade."

Rhyolite is an igneous, volcanic (extrusive) rock, of felsic (silicon-rich) composition (typically >69% SiO2 — see the TAS classification). It may have any texture from aphanitic to porphyritic. The mineral assemblage is usually quartz, alkali feldspar and plagioclase (in a ratio > 1:2 — see the QAPF diagram). Biotite and hornblende are common accessory minerals.

Rhyolite can be considered as the extrusive equivalent to the plutonic granite rock, and consequently, outcroppings of it often bear a resemblance to granite. Due to their high content of silica and low iron and magnesium contents, rhyolite melts are highly polymerized and form highly viscous lavas. They can also occur as breccias or in volcanic plugs and dykes. Rhyolites that cool too quickly to grow crystals form a natural glass or vitrophyre, also called obsidian. Slower cooling forms microscopic crystals in the lava and results in textures such as flow foliations, spherulitic, nodular, and lithophysal structures. Some rhyolite is highly vesicular pumice. Many eruptions of rhyolite are highly explosive and the deposits may consist of fallout tephra or of ignimbrites.

ee also

*List of rock types

References

* [http://volcano.und.edu/vwdocs/vwlessons/lessons/Slideshow/Igrocks/Igrock9.html University of North Dakota description of rhyolite]
* [http://www.rocks-rock.com/rhyolite.html Information from rocks-rock.com]


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  • Rhyolite — Rhy o*lite, n. [Gr. rei^n to flow + lite.] (Min.) A quartzose trachyte, an igneous rock often showing a fluidal structure. {Rhy o*lit ic},, a. [1913 Webster] …   The Collaborative International Dictionary of English

  • rhyolite — [rī′ə līt΄] n. [Ger rhyolit < Gr rhyax, stream (of lava) + lithos, stone] a light colored igneous rock with a fine grained, granitelike texture …   English World dictionary

  • Rhyolite — Früheres Bahnhofsgebäude von Rhyolite …   Deutsch Wikipedia

  • Rhyolite — Pour les articles homonymes, voir Rhyolite (homonymie). Rhyolite Rhyolite. Les cristaux de feldspath (rose clair) et de …   Wikipédia en Français

  • rhyolite — ALASKA VOLCANO OBSERVATORY GLOSSARY Volcanic rock (or lava) that characteristically is light in color, contains 69% silica or more, and is rich in potassium and sodium. GLOSSARY OF VOLCANIC TERMS A volcanic rock containing greater than 68% silica …   Glossary of volcanic terms

  • rhyolite — rhyolitic /ruy euh lit ik/, adj. /ruy euh luyt /, n. a fine grained igneous rock rich in silica: the volcanic equivalent of granite. [1865 70; rhyo (irreg. < Gk rhýax stream of lava) + LITE] * * * Igneous rock that is the volcanic equivalent of… …   Universalium

  • rhyolite — rhyolithe ou rhyolite [ rjɔlit ] n. f. • 1883; du gr. rhuô, de rhein « couler », et lithe ♦ Géol. Lave volcanique de composition granitique, à texture souvent porphyrique, dont la pâte est partiellement vitreuse. ● rhyolite nom féminin Roche… …   Encyclopédie Universelle

  • rhyolite — noun Etymology: German Rhyolith, from Greek rhyax stream, stream of lava (from rhein) + German lith lite Date: 1868 a very acid volcanic rock that is the lava form of granite • rhyolitic adjective …   New Collegiate Dictionary

  • rhyolite — noun An igneous, volcanic (extrusive) rock, of felsic composition, with aphanitic to porphyritic texture …   Wiktionary

  • rhyolite — [ rʌɪəlʌɪt] noun Geology a pale fine grained volcanic rock of granitic composition. Origin C19: from Ger. Rhyolit, from Gk rhuax lava stream + lithos stone …   English new terms dictionary


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