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Study with Quizlet and memorize flashcards containing terms like Coarse-grained granite is most similar in mineral composition to fine-grained _____., If magma or lava cools quickly, the resulting igneous rock will have _____., Intrusive igneous rocks are often coarse-grained because _____. and more.
An igneous rock with a mixed texture of coarse crystals (phenocrysts) surrounded by fine crystals (groundmass) is termed _____. A. porphyritic B. phaneritic C. aphanitic D. necrotic
Study with Quizlet and memorize flashcards containing terms like Most commonly, felsic igneous rocks _____. A. contain more iron and magnesium than intermediate rocks B. are lighter in color than mafic rocks C. are darker in color than mafic rocks D. are found in oceanic crust, Which of the following silicate minerals is often found in granite?
3. Mafic Igneous Rocks. Definition: Mafic rocks have a lower silica content (45-52%) and are rich in iron and magnesium. The term “mafic” combines “magnesium” and “ferric” (iron). Characteristics: These rocks are darker in color, typically grey, green, or black. They are denser than felsic rocks. Examples:
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine , pyroxene , amphibole , and biotite .
Mafic rock, in geology, igneous rock that is dominated by the silicates pyroxene, amphibole, olivine, and mica. These minerals are high in magnesium and ferric oxides, and their presence gives mafic rock its characteristic dark colour.
Magnetite, ilmenite, and apatite are common as accessory minerals in mafic and intermediate rocks. The photos below (Figures 6.109 to 6.116) show some of the most common intermediate and mafic rocks.
Mafic rocks are dark-colored igneous rocks rich in magnesium and calcium. These rocks are rich in minerals like pyroxene, olivine, hornblende, and biotite and are associated with calcium-rich plagioclase. Chemically, mafic rocks are relatively low in silica. They usually have 45-52 wt. % silica. Rocks with less than 45 wt. % silica are ultramafic.
Felsic and mafic rocks, division of igneous rocks on the basis of their silica content. Chemical analyses of the most abundant components in rocks usually are presented as oxides of the elements; igneous rocks typically consist of approximately 12 major oxides totaling over 99 percent of the rock.
Igneous rocks can be classified based on their chemical and mineral composition into four primary categories: ultramafic, mafic, intermediate, and felsic. Here’s a detailed overview of each category including their composition, characteristics, examples, and formation processes.