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Acid Magma Felsic Magmas

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Yosemite Granite USGS white appearing minerals are quartz and feldspars. Black specs biotite mica and amphiboleAcid or felsic magmas are enriched in silicon,oxygen,aluminium,sodium and potassium. The common minerals are quartz ( SiO2),muscovite (mica) ,orthoclase feldspar and plagioclase feldspars and are light in colour and are lower density than darker iron rich minerals. Acid or Felsic magmas solidify form rocks with a silica content less than 63%. Acid/Felsic magmas solidify in the crust commonly as granite and erupt as rhyolite lavas. Within an intrusion crystals grow large within the magma chamber. Pumice and Obsidian are eruptive forms of the same composition.