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What are felsic and mafic rocks?
What is the difference between felsic igneous and mafic magma?
What is the difference between felsic and mafic composition?
How do you know if a rock is felsic or mafic?
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.
- Mafic Rock
Mafic rock is commonly contrasted with felsic rock, in...
- Quartz Monzonite
It is abundant in the large batholiths (great masses of...
- Syenite
Syenite, any of a class of intrusive igneous rocks...
- Intermediate
Other articles where intermediate rock is discussed: felsic...
- Ultramafic
Ultramafic metamorphic rocks result from the metamorphism of...
- Gabbro
gabbro, any of several medium- or coarse-grained rocks that...
- Peridotite
Peridotite is the ultimate source of all chromium ore and...
- Mafic Rock
Jan 31, 2024 · Light-colored rocks (high in silica) suggest a felsic composition (e.g., granite, rhyolite). Dark-colored rocks indicate a mafic or ultramafic composition (e.g., basalt, gabbro). Texture: Coarse-grained textures where minerals are easily visible are characteristic of plutonic rocks, such as granite.
For igneous rock, the composition is divided into four groups: felsic, intermediate, mafic, and ultramafic. These groups refer to differing amounts of silica, iron, and magnesium found in the minerals that make up the rocks.
- Classification by Mineral Abundance
- Classification by Grain Size
- Classifying Igneous Rocks According to The Proportion of Dark Minerals
- Classifying Igneous Rocks When Individual Crystals Are Not Visible
Igneous rocks can be divided into four categories based on their chemical composition: felsic, intermediate, mafic, and ultramafic. The diagram of Bowen’s reaction series (Figure 4.6) shows that differences in chemical composition correspond to differences in the types of minerals within an igneous rock. Igneous rocks are given names based on the p...
The name an igneous rock gets also depends on whether it cools within Earth (an intrusive or plutonic igneous rock), or whether it cools on the Earth’s surface after erupting from a volcano (an extrusive or volcanic igneous rock). For example, a felsic intrusive rock is called granite, whereas a felsic extrusive rock is called rhyolite. Granite and...
If you unsure of which minerals are present in an intrusive igneous rock, there is a quick way to approximate the composition of that rock. In general, igneous rocks have an increasing proportion of dark minerals as they become more mafic (Figure 4.16). The dark-colored minerals are those higher in iron and magnesium (e.g., olivine, pyroxene, amphi...
The method of estimating the percentage of minerals works well for phaneritic igneous rocks, in which individual crystals are visible with little to no magnification. If an igneous rock is porphyritic but otherwise aphanitic (e.g., Figure 4.14), the minerals present as phenocrysts give clues to the identity of the rock. However, there are cases whe...
- Granite is an igneous rock used commonly in statues and building materials.
- Pumice is a light igneous rock used for abrasive materials.
- This landscape high in California’s Sierra Nevada is completely made up of granite exposed at Earth’s surface.
- A close-up of a granite sample. Notice the black and white portions. Each color represents a different mineral in the rock. You can easily see the mineral crystals that make up this plutonic igneous rock.
Composition influences the color of igneous rocks. Felsic rocks tend to be light in color (white, pink, tan, light brown, light gray). Mafic rocks tend to be dark in color (black, very dark brown, very dark gray, dark green mixed with black). The color distinction comes from the differences in iron and magnesium content.
Dec 12, 2023 · Felsic and mafic are field terms we use to classify igneous rocks, their magma, or lava. This classification is based on their mineral composition, i.e., silicates they have. Silicates are the most common and important rock-forming minerals. They make up over 90% of the Earth’s crust. What are silicates?
