Dark-colored rocks with low silica contents
generally falling between 44 and 52 percent. They include
one of four groups of rocks classified based on silica content,
including ultramafic (less than 44 percent SiO2), basic, intermediate
(53–65 percent SiO2), and silicic (greater than 65
percent SiO2). They are generally dark colored, and include
basalt, gabbro, and related rocks. Basic rocks are typically
rich in iron (Fe) and magnesium (Mg) and are also known as
mafic rocks.
See also IGNEOUS ROCKS.
generally falling between 44 and 52 percent. They include
one of four groups of rocks classified based on silica content,
including ultramafic (less than 44 percent SiO2), basic, intermediate
(53–65 percent SiO2), and silicic (greater than 65
percent SiO2). They are generally dark colored, and include
basalt, gabbro, and related rocks. Basic rocks are typically
rich in iron (Fe) and magnesium (Mg) and are also known as
mafic rocks.
See also IGNEOUS ROCKS.
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