This page is about a volcanic rock. For the ghost town see Rhyolite, Nevada, and for the satellite system, see Rhyolite/Aquacade. Rhyolite Nevada is a Ghost town in Nye County, Nevada, United States. Rhyolite and later Aquacade are reportedly code names for a class of SIGINT Reconnaissance satellites operated by the National Reconnaissance Office

Rhyolite

Rhyolite is an igneous, volcanic (extrusive) rock, of felsic (silicon-rich) composition (typically >69% SiO₂ — see the TAS classification). Igneous rocks (etymology from Latin ignis, fire are rocks formed by solidification of cooled Magma (molten rock Extrusive refers to the mode of Igneous Volcanic rock formation in which hot Magma from inside the Earth flows out (extrudes onto the surface In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere Felsic is a term used in Geology to refer to Silicate minerals, Magma, and rocks which are enriched in the lighter elements such as Silicon Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 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. Porphyry is a variety of Igneous rock consisting of large-grained Crystals such as Feldspar or Quartz, dispersed in a fine-grained The mineral assemblage is usually quartz, alkali feldspar and plagioclase (in a ratio > 1:2 — see the QAPF diagram). A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific Quartz (from German) is the most abundant Mineral in the Earth 's Continental crust (although Feldspar is more common in In Chemistry, an alkali (from Arabic: Al-Qaly القلي القالي) is a basic, ionic salt of an Alkali metal Feldspar is the name of a group of rock-forming Minerals which make up as much as 60% of the Earth 's crust. Plagioclase is a very important series of tectosilicate Minerals within the Feldspar family A QAPF diagram is a double triangle Diagram which is used to classify Igneous rocks based on mineralogic composition Biotite and hornblende are common accessory minerals. Biotite is a common phyllosilicate Mineral within the Mica group with the approximate chemical formula K(Mg Fe3AlSi3O10(F Hornblende is a complex inosilicate 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

Rhyolite can be considered as the extrusive equivalent to the plutonic granite rock, and consequently, outcroppings of it often bear a resemblance to granite. Extrusive refers to the mode of Igneous Volcanic rock formation in which hot Magma from inside the Earth flows out (extrudes onto the surface In Geology, an intrusion is a body of Igneous rock that has Crystallized from molten Magma below the surface of the Earth. Granite (ˈɡrænɪt is a common and widely occurring type of intrusive, Felsic, igneous rock. Due to their high content of silica and low iron and magnesium contents, rhyolite melts are highly polymerized and form highly viscous lavas. Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures They can also occur as breccias or in volcanic necks and dykes. Breccia (ˈbrɛtʃiə ˈbrɛʃiə breach is a rock composed of angular fragments of several Minerals or rocks in a matrix, that is a cementing material Plate tectonics and hotspots Divergent plate boundaries At the A dike or dyke in Geology is a type of Sheet intrusion referring to any geologic body that cuts Discordantly ' across planar Rhyolites that cool too quickly to grow crystals form a natural glass or vitrophyre, also called obsidian. Obsidian is a naturally occurring Glass formed as an extrusive Igneous rock. Slower cooling forms microscopic crystals in the lava and results in textures such as flow foliations, spherulitic, nodular, and lithophysal structures. Foliation is any penetrative planar fabric present in rocks. Foliation is common to rocks affected by regional metamorphic compression typical of orogenic Spherulites, in Petrology, are small rounded bodies that commonly occur in Vitreous Igneous rocks They are often visible in specimens of Obsidian A nodule in Petrology or Mineralogy is a secondary structure generally spherical or irregularly rounded in shape A lithophysa (plural lithophysae) is a small cavity found in Felsic Volcanic rocks believed to be caused by expanding gases in Tuffs Some rhyolite is highly vesicular pumice. Pumice is a textural term for a volcanic rock that is a solidified frothy lava composed of highly microvesicular glass Pyroclastic with very thin translucent Many eruptions of rhyolite are highly explosive and the deposits may consist of fallout tephra or of ignimbrites. Tephra is air-fall material produced by a volcanic eruption regardless of composition or fragment size Ignimbrite is a Volcanic Pyroclastic rock often of Dacitic or Rhyolitic composition

Top stone is obsidian, below that is pumice and in lower right corner is rhyolite (light color)

See also

• List of rock types

References

• University of North Dakota description of rhyolite
• Information from rocks-rock.com