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Felsic magmas and lavas have lower temperatures of melting and solidification than mafic magmas and lavas. Felsic rocks are usually light in color and have specific gravities less than 3. The most common felsic rock is granite. Common felsic minerals include quartz, muscovite, orthoclase, and the sodium-rich plagioclase feldspars (albite-rich).
Granite (/ ˈ ɡ r æ n ɪ t / GRAN-it) is a coarse-grained intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies underground. It is common in the continental crust of Earth, where it is found in igneous ...
Quartzolite – Extremely rare igneous rock made mostly of quartz – An intrusive rock composed mostly of quartz; Rhyodacite – Volcanic rock rich in silica and low in alkali metal oxides – A felsic volcanic rock which is intermediate between a rhyolite and a dacite; Rhyolite – Igneous, volcanic rock, of felsic (silica-rich) composition
Igneous rock (igneous from Latin igneus 'fiery'), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial melts of existing rocks in either a planet 's mantle or crust.
Porphyry (geology) Porphyry (/ ˈpɔːrfəri / POR-fə-ree) is any of various granites or igneous rocks with coarse-grained crystals such as feldspar or quartz dispersed in a fine-grained silicate -rich, generally aphanitic matrix or groundmass. In its non-geologic, traditional use, the term porphyry usually refers to the purple-red form of ...
These rocks are largely igneous in origin, mixed with metamorphosed marble, quartzite and mica schist with later intrusions of basaltic dikes and granite magma. [21] The Morton Gneiss is an Archean-age gneiss exposed in the Minnesota River Valley of southwestern Minnesota, United States. It is thought to be the oldest intact block of ...
Felsite is a very fine-grained volcanic rock that may or may not contain larger crystals. Felsite is a field term for a light-colored rock that typically requires petrographic examination or chemical analysis for more precise definition. Color is generally white through light gray, or red to tan and may include any color except dark gray, green ...
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