Rhyolite

	Email		Print
	Bookmark		Link

Rhyolite

This page is about a volcanic rock. For the ghost town see Rhyolite, Nevada
Rhyolite, Nevada

Rhyolite is a ghost town in Nye County, Nevada, in the U.S. state of Nevada. It is located in the Bullfrog Hills, about west of the town of Beatty, Nevada, near the eastern edge of Death Valley....
, and for the satellite system, see Rhyolite/Aquacade
Rhyolite/Aquacade

Rhyolite and later, Aquacade are reportedly code names for a class of SIGINT reconnaissance satellites operated by the National Reconnaissance Office for the United States Central Intelligence Agency....
. Rhyolite is an igneous

Igneous rock

Igneous rock is one of the three main Rock types . Igneous rock is formed by magma being cooled and becoming solid . They may form with or without crystallization, either below the surface as Intrusion rocks or on the surface as extrusive rocks....
, volcanic (extrusive) rock

Rock (geology)

In geology, rock is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock....
, of felsic

Felsic

Felsic is a term used in geology to refer to silicate minerals, magma, and rock which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium....
(silicon

Silicon

Silicon is the most common metalloid. It is a chemical element, which has the symbol Si and atomic number 14. The atomic mass is 28.0855....
-rich) composition (typically >69% SiO₂ — see the TAS classification

TAS classification

The TAS classification can be used to assign names to many common types of volcanic rocks based upon the relationships between the combined alkali content and the silica content....
). It may have any texture from aphanitic to porphyritic.

Discussion

Ask a question about 'Rhyolite'

Start a new discussion about 'Rhyolite'

Answer questions from other users

Full Discussion Forum

Encyclopedia

Rhyolite is an igneous

Igneous rock

Rock (geology)

In geology, rock is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock....
, of felsic

Felsic

Felsic is a term used in geology to refer to silicate minerals, magma, and rock which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium....
(silicon

Silicon

TAS classification

Mineral

A mineral is a naturally occurring solid formed through Geology processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties....
assemblage is usually quartz

Quartz

Quartz is the most abundant mineral in the Earth's continental crust . It is made up of a Crystal structure of silica tetrahedra. Quartz has a hardness of 7 on the Mohs scale and a density of 2.65 g/cm?....
, alkali

Alkali

In chemistry, an alkali is a Base , Ionic compound salt of an alkali metal or alkaline earth metal Chemical element. Alkalis are best known for being Base s that dissolve in water....
feldspar

Feldspar

Feldspars are a group of rock-forming tectosilicate minerals which make up as much as 60% of the Earth's Crust .Feldspars crystallize from magma in both intrusive and extrusive igneous rocks, as veins, and are also present in many types of metamorphic rock....
and plagioclase

Plagioclase

Plagioclase is a very important series of Silicate minerals minerals within the feldspar family. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a solid solution series, more properly known as the plagioclase feldspar series ....
(in a ratio > 1:2 — see the QAPF diagram

QAPF diagram

A QAPF diagram is a double triangle diagram which is used to classify igneous rocks based on mineralogy composition. The acronym, QAPF, stands for "Quartz, feldspar, Plagioclase, Feldspathoid "....
). Biotite

Biotite

Biotite is a common Silicate minerals#Phyllosilicates mineral within the mica group, with the approximate chemical formula K3AlSi3O102....
and hornblende

Hornblende

Hornblende is a complex silicate minerals series of minerals. Hornblende is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole....
are common accessory minerals.

Rhyolite can be considered as the extrusive equivalent to the plutonic granite

Granite

Granite is a common and widely occurring type of Intrusion , felsic, igneous rock rock . Granite has a medium to coarse texture, occasionally with some individual crystals larger than the groundmass forming a rock known as Porphyry ....
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 lava

Lava

Lava is molten Rock expelled by a volcano during an eruption. When first expelled from a volcanic vent, it is a liquid at temperatures from 700 ?C to 1,200 ?C ....
s. They can also occur as breccia

Breccia

Breccia is a rock composed of angular fragments of several minerals or rocks in a Matrix , that is a Cementation material, that may be similar or different in composition to the fragments....
s or in volcanic plug

Volcanic plug

A volcanic plug, also called a volcanic neck or lava neck, is a volcano landform created when magma hardens within a vent on an active volcano....
s and dikes

Dike (geology)

A dike or dyke in geology is a type of sheet intrusion referring to any geologic body that cuts discordantly across* planar wall rock structures, such as bedding or foliation...
. Rhyolites that cool too quickly to grow crystals form a natural glass or vitrophyre, also called obsidian

Obsidian

Obsidian is a naturally occurring glass formed as an extrusive igneous rock. It is produced when felsic lava extruded from a volcano cools without crystal growth....
. Slower cooling forms microscopic crystals in the lava and results in textures such as flow foliations

Foliation (geology)

Foliation is any penetrative planar Fabric present in Rock . Foliation is common to rocks affected by regional metamorphism compression typical of orogeny....
, spherulitic

Spherulite

Spherulites, in petrology, are small, rounded bodies that commonly occur in vitreous igneous rocks. They are often visible in specimens of obsidian, pitchstone and rhyolite as globules about the size of millet seed or rice grain, with a duller Lustre than the surrounding glassy base of the rock, and when they are examined with a lens they...
, nodular

Nodule (geology)

A nodule in petrology or mineralogy is a secondary structure, generally spherical or irregularly rounded in shape. Nodules are typically solid replacement bodies of chert or iron oxides formed during diagenesis of a sedimentary rock....
, and lithophysal

Lithophysa

A lithophysa is a small cavity found in felsic volcanic Rock believed to be caused by expanding gases in tuffs before solidification. If it has become lined with crystals it may be referred to as a geode or a thunderegg....
structures. Some rhyolite is highly vesicular

Vesicular texture

Vesicular texture is a volcanic Rock texture characterised by, or containing, many vesicles. The texture is often found in extrusive aphanite, or glassy, igneous rock....
pumice

Pumice

File:Pumice stone444.jpgFile:Pumice stone detail444.jpgPumice is a textural term for a volcanic rock that is a solidified frothy lava typically created when super-heated, highly pressurized rock is violently ejected from a volcano....
. Many eruptions of rhyolite are highly explosive and the deposits may consist of fallout tephra

Tephra

Tephra is air-fall material produced by a Volcano regardless of composition or fragment size. Tephra is typically Rhyolite in composition, as most explosive volcanoes are the product of the more viscosity felsic or high silica magmas....
or of ignimbrite

Ignimbrite

Ignimbrite is a volcano pyroclastic rock, often of dacitic or rhyolitic composition."Ignimbrite" is the deposit of a pumice rich pyroclastic density current, or 'pyroclastic flow', a hot suspension of particles and gases that flows rapidly from a volcano, driven by a greater density than the surrounding atmosphere....
s.

Rhyolite

See also