Changes

Volcanic rock (or lava) that characteristically is light in color, contains 69 percent [[silica]] or more, and is rich in [[potassium]] and [[sodium]]. <ref>[http://vulcan.wr.usgs.gov/Glossary/volcano_terminology.html Glossary of Volcano and Related Terminology (Foxworthy and Hill, 1982) ]</ref>

[[Image:Rhyolite.jpg|thumb|300px|Flow banding in rhyolite lava from Mono-Inyo Craters volcanic chain, California (black bands composed of obsidian)]]Volcanic rock (or lava) that characteristically is light in color, contains 69 percent [[silica]] or more, and is rich in [[potassium]] and [[sodium]]. <ref>[http://vulcan.wr.usgs.gov/Glossary/volcano_terminology.html Glossary of Volcano and Related Terminology (Foxworthy and Hill, 1982) ]</ref>

'''Rhyolite''' is a light-colored rock with [[silica]] (SiO2) content greater than about 68 weight percent. [[Sodium]] and [[potassium]] [[oxides]] both can reach about 5 weight percent. Common mineral types include [[quartz]], [[feldspar]] and [[biotite]] and are often found in a glassy [[matrix]]. Rhyolite is erupted at temperatures of 700 to 850° C.  <ref>[http://vulcan.wr.usgs.gov/Glossary/volcano_terminology.html Glossary of Volcano and Related Terminology (USGS/VHP)]</ref>

'''Rhyolite''' is a light-colored rock with [[silica]] (SiO2) content greater than about 68 weight percent. [[Sodium]] and [[potassium]] [[oxides]] both can reach about 5 weight percent. Common mineral types include [[quartz]], [[feldspar]] and [[biotite]] and are often found in a glassy [[matrix]]. Rhyolite is erupted at temperatures of 700 to 850° C.  <ref>[http://vulcan.wr.usgs.gov/Glossary/volcano_terminology.html Glossary of Volcano and Related Terminology (USGS/VHP)]</ref>