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Rhyolite is an igneous, volcanic ( extrusive) rock, of felsic composition, with aphanitic to porphyritic texture. Mineral assembly is usually quartz, alkali feldspar and plagioclase (in a ratio > 1:2). Biotite and pyroxene are common accessory minerals.Rhyolite can be considered as the extrusive equivalent to the plutonic granite rock. Due to their high content of silica, rhyolite form highly viscous lavas. They can also occur as breccias or in volcanic necks and dikes. Like obsidianObsidian is a type of naturally occurring glass, produced from volcanoes when the right kind of lava cools rapidly, e. by flowing into a body of water. It consists mainly of SiO (silicon dioxide), 70% or more. Obsidian is mineral-like, but not a true mine, rhyolites frequently show flow, spherulitic, nodular, and lithophysal structures.
Top stone is obsidianObsidian is a type of naturally occurring glass, produced from volcanoes when the right kind of lava cools rapidly, e. by flowing into a body of water. It consists mainly of SiO (silicon dioxide), 70% or more. Obsidian is mineral-like, but not a true mine, below that is pumiceobsidian, below that is pumice and in lower right hand color is rhyolite (light color). Pumice is a light, porous type of pyroclastic igneous rock. It is formed during explosive volcanic eruptions when liquid lava is ejected into the air as a froth contai and in lower right corner is rhyolite (light color)
See also: igneous rocks, list of rocksThis page is intended as a list of all rock types. See also: List of minerals List of stone Earth science mineralogy mineraloid rock metamorphic rock igneous rock sedimentary rock Sorted by name: A : Amphibolite : Andesite : Anorthosite : Aplite B : Basal, granite
Igneous rocks
VolcanologyVolcanology (also spelled vulcanology is the study of volcanoes, lava, magma and related geological phenomena. A volcanologist (also spelled vulcanologist is a person who studies in this field. Volcanologists frequently visit volcanoes, especially active
