A: Water content, silicate content, and the most important part speed of cooling are the three factors that influence the texture of igneous rocks. 2. The three major compositional groups for igneous rocks are mafic, intermediate and felsic.
Hereof, what affects the texture of igneous rocks?
The main factors that can affect the texture of an igneous rock are the location and cooling rate of the hot magma that forms the rock.
Likewise, what factors affect the physical appearance of igneous rocks? The type of igneous rocks that form from magma is a function of three factors: the chemical composition of the magma; temperature of solidification; and the rate of cooling which influences the crystallization process.
Considering this, what factor of formation most influences the texture of igneous rock?
The texture in igneous rocks depends on the following four factors: i) Viscosity of magma ii) Rate of cooling iii) The order of crystallization of the constituent minerals. iv) The relative rates of growth of the constituent minerals.
What are the six major igneous rock textures?
Igneous textures are used by geologists in determining the mode of origin igneous rocks and are used in rock classification. There are six main types of textures; phaneritic, aphanitic, porphyritic, glassy, pyroclastic and pegmatitic.
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What are the classification of igneous rocks?
As has already been described, igneous rocks are classified into four categories, based on either their chemistry or their mineral composition: felsic, intermediate, mafic, and ultramafic. The diagram in Figure 3.16 can be used to help classify igneous rocks by their mineral composition.
What does the texture of an igneous rock tell you?
The individual crystals in an aphanitic igneous rock are not distinguishable to the naked eye. Phaneritic (phaner = visible) textures are typical of intrusive igneous rocks, these rocks crystallized slowly below Earth’s surface. As magma cools slowly the minerals have time to grow and form large crystals.
What is texture of a rock?
The texture of a rock is the size, shape, and arrangement of the grains (for sedimentary rocks) or crystals (for igneous and metamorphic rocks). Also of importance are the rock’s extent of homogeneity (i.e., uniformity of composition throughout) and the degree of isotropy. The…
What are the main characteristics of igneous rocks?
Here are some characteristics of igneous rocks : Normally contains no fossils. Rarely reacts with acid. Usually has no layering. Usually made of two or more minerals. May be light or dark colored. Usually made of mineral crystals of different sizes. Sometimes has openings or glass fibers.
What does a igneous rock feel like?
Extrusive Igneous Rocks: Quick cooling means that mineral crystals don’t have much time to grow, so these rocks have a very fine-grained or even glassy texture. Hot gas bubbles are often trapped in the quenched lava, forming a bubbly, vesicular texture.
What is the texture of basalt?
Basalt has a fine-grained mineral texture due to the molten rock cooling too quickly for large mineral crystals to grow; it is often porphyritic, containing larger crystals (phenocrysts) formed prior to the extrusion that brought the magma to the surface, embedded in a finer-grained matrix.
What is a porphyritic texture?
Porphyritic texture is a very common texture in igneous rocks in which larger crystals (phenocrysts) are embedded in a fine-grained groundmass. Porphyry is an igneous rock that contains larger crystals (phenocrysts) in a fine-grained groundmass. K-feldspar phenocrysts in this sample.
What determines grain size of igneous rock?
Answer and Explanation: The size of grains in igneous rocks is mainly determined by how quickly the magma cooled down. If the magma cools very slowly, the crystals have a
What does Equigranular mean?
: having or characterized by crystals of nearly the same size a rock of equigranular texture.
What is the structure of igneous rock?
An igneous rock is any crystalline or glassy rock that forms from cooling of a magma. A magma consists mostly of liquid rock matter, but may contain crystals of various minerals, and may contain a gas phase that may be dissolved in the liquid or may be present as a separate gas phase.
What is the composition and texture of igneous rocks?
Igneous rocks are classified according to their texture and composition. Composition refers to both the types of minerals within a rock and the overall chemical makeup of the rock (the two are obviously related). Texture refers to the size and arrangement of the minerals or grains that make up a rock.
What is granular texture?
Definition of granular texture. A rock texture resulting from the aggregation of mineral grains of approx. used to describe an equigranular, holocrystalline igneous rock whose particles range in diameter from 0.05 to 10 mm.
What is the texture of pegmatite?
Pegmatitic Textures. A pegmatitic texture is one in which the mineral grains are exceptionally large. This texture is found in intrusive rocks. The extra large size does not mean that they cooled extra slowly. Instead, the large crystals of a pegmatite formed in a magma that was extra rich in dissolved water.