rhyolite


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rhyolite,

fine-grained light-colored acidic volcanic rockrock,
aggregation of solid matter composed of one or more of the minerals forming the earth's crust. The scientific study of rocks is called petrology. Rocks are commonly divided, according to their origin, into three major classes—igneous, sedimentary, and metamorphic.
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. Rhyolite is chemically the equivalent of granite, and is thus composed primarily of quartz and orthoclase feldspar with subordinate amounts of plagioclase feldspar, biotite mica, amphiboles, and pyroxenes. Rhyolite lava exhibits a typical banded structure produced by its flow pattern. Rhyolite lavas occur in continental and submarine volcanoes, especially island arcs, and in igneous dikes. Rhyolite lavas are typically highly viscous and are explosively ejected from volcanoes. Rhyolites were formed in profusion in the Yellowstone Park area and throughout the southwestern portion of the United States.

Rhyolite

 

(also liparite), a cenotypal, extrusive rock rich in silica (68-77 percent SiO2). It has a porphyritic texture and contains phenocrysts of quartz, potassium feldspar, plagioclase, and, less commonly, biotite or pyroxene in a glassy groundmass, usually with flow texture. A glassy variety virtually without phenocrysts is called obsidian. Paleotypal analogs are classified according to their alkali composition as keratophyres (sodic) or orthophyres (potassic). Rhyolite is the extrusive equivalent of granitoids.

rhyolite

[′rī·ə‚līt]
(petrology)
A light-colored, aphanitic volcanic rock composed largely of alkali feldspar and free silica with minor amounts of mafic minerals; the extrusive equivalent of granite.
References in periodicals archive ?
The granites occur in stocks, bosses and dykes that are accompanied by felsic to mafic dykes, and rhyolite plugs (Kazmi and Khan, 1973; Butt et al.
Our tarp-enveloped rhyolite boulders fore-grounded this slow, entropic collapse of the manufactured space and nonhuman reclamation of the void.
Preliminary flotation and leaching test work suggests uranium can be separated and leached from the rhyolite host rock, but uranium extraction was not considered in the PEA.
Resultsto date highlight the potential of coincident NW and NE trending structures, favourable host rocks and subsurface rhyolite domes to host sizeable zones of mineralization in areas beyond the initial resource outline.
In this paper, we selected key samples from the Cumberland Hill Formation in order to petrologically and geochemically characterize the rocks and compare the rhyolite and trachyte to similar rocks elsewhere in the Maritimes Basin.
The Guacamayas Volcanic rocks have been grouped from old to young in: a) Teresen Rhyolitic Suite composed by flows of rhyolitic lavas interlayered with ash tuffs, agglomerate and sandstone, whose stratigraphic relations allow to separate three volcanic episodes with its pyroclastics equivalent, that from bottom up are: Corcovado Rhyolite, Tirado Rhyolite and La Bandola Rhyolite; b) El Penon Latitic Suite is composed by a sequence of porphyritic latitic lavas and flows of glassy tuffs that culminate in a thick accumulation of tuffs and agglomerates; it is divided in two subunits (El Oso Quartz Latite, Segoviera Rhyolite) with transitional contact between them.
But the financial panic of 1907 took its toll on Rhyolite and promulgated the end of the town's prosperity.
Once at Massai Point, you'll see an exhibit tracing the geological evolution of the Rhyolite Canyon formation, from layers of once-glowing ash and burning sand to columns of rock, some balancing huge heads on precarious pinnacles, as at Big Balanced Rock.
A basal layer of the unit is breccia comprising rhyolite and mudstone blocks and less common sulphide fragments in a chaotic, black matrix.
This stage is marked by an enigmatic type of rock -- red granites and rhyolites -- appearing in a broad belt that stretches several thousand miles from southern California to Labrador.
6 grams per tonne of uranium the Round Top rhyolite may contain an estimated 101.
Contractor name : N&B SOLUTIONS DUNS: 830163916 4144 SOUTH WEST RHYOLITE PLACE REDMOND OR 97756