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intermediate rock
geology
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felsic and mafic rock classification
- In felsic and mafic rocks
…and 65 percent silica are intermediate; those with between 45 and 55 percent silica are mafic; and those with less than 45 percent are ultramafic. Compilations of many rock analyses show that rhyolite and granite are felsic, with an average silica content of about 72 percent; syenite, diorite, and monzonite…
Read More - In igneous rock: Chemical components
…more than 66 percent silica; intermediate, rocks with 55 to 66 percent silica; and subsilicic, rocks containing less than 55 percent silica. The latter may be further divided into two groups: mafic, rocks with 45 to 55 percent silica and ultramafic, those containing less than 45 percent. The subsilicic rocks,…
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