Classification of igneous rocks based on composition
What are compositions of igneous rocks?
Composition refers to a rock’s chemical and mineral make-up. 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.
What are the three main compositions of igneous rocks?
Igneous Rocks: textures and compositions
| Felsic | Mafic | |
|---|---|---|
| Coarse- grained | granite | gabbro |
| Fine- grained | rhyolite | basalt |
| Minerals | quartz, K-feldspar, amphibole, muscovite, biotite | olivine, pyroxene, Ca-feldspar (plagioclase) |
23 Feb 2005
What are the 2 basic classifications of igneous rocks?
Igneous rocks are divided into two groups, intrusive or extrusive, depending upon where the molten rock solidifies.
What are the 6 different igneous rocks and how are they classified?
Igneous Rock Textures
There are six main types of textures; phaneritic, aphanitic, porphyritic, glassy, pyroclastic and pegmatitic. Aphanitic (a = not, phaner = visible) rocks in contrast to phaneritic rocks, typically form from lava which crystallize rapidly on or near Earth’ surface.
What is the composition of a rock?
Rocks are composed primarily of grains of minerals, which are crystalline solids formed from atoms chemically bonded into an orderly structure. Some rocks also contain mineraloids, which are rigid, mineral-like substances, such as volcanic glass, that lacks crystalline structure.
What is the difference between the composition of felsic and mafic igneous rocks?
In a widely accepted silica-content classification scheme, rocks with more than 65 percent silica are called felsic; those with between 55 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.
Which feature is used to classify a rock based on its composition?
CLASSIFICATION The classification of rocks is based on two criteria, TEXTURE and COMPOSITION. The texture has to do with the sizes and shapes of mineral grains and other constituents in a rock, and how these sizes and shapes relate to each other. Such factors are controlled by the process which formed the rock.
What is the classification of igneous rocks based on quizlet?
Igneous rocks are classified according to their origin, texture and mineral composition. A igneous rock formed from lava that erupted on to earths surface. A igneous rock that formed when magma hardened beneath Earth’s surface. Includes extrusive, intrusive igneous rocks.
How do you read an igneous rock classification chart?
What are the main features of igneous rocks?
Characteristics of Igneous Rocks
- The igneous form of rocks does not include any fossil deposits. …
- Most igneous forms include more than one mineral deposit.
- They can be either glassy or coarse.
- These usually do not react with acids.
- The mineral deposits are available in the form of patches with different sizes.
What is the texture and composition of igneous rocks?
Igneous rocks may be simply classified according to their chemical/mineral composition as felsic, intermediate, mafic, and ultramafic, and by texture or grain size: intrusive rocks are course grained (all crystals are visible to the naked eye) while extrusive rocks may be fine-grained (microscopic crystals) or glass ( …
What is the composition of metamorphic rocks?
Composition. Common minerals in metamorphic rocks include quartz, feldspar, mica, calcite, and hornblende. Index minerals in metamorphic rocks indicate how much the original rock was metamorphosed, called the grade of metamorphism.
What is the composition of felsic?
Felsic refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. Felsic magma or lava is higher in viscosity than mafic magma/lava. Felsic rocks are usually light in color and have specific gravities less than 3.
How do you determine the composition of an igneous rock?
An easy method of determining the igneous rock composition is by determining the percentage of dark-colored minerals in the rock, without trying to identify the actual minerals present; this method of classification relies on a mafic color index (MCI), where the term mafic refers to any dark gray, black, or green- …
What is mafic and felsic?
Either in describing rocks or lava, mafic means that the lava or rock has less silica while felsic implies that the lava or rock has the most silica.
Which feature is used to classify a rock based on its composition?
CLASSIFICATION The classification of rocks is based on two criteria, TEXTURE and COMPOSITION. The texture has to do with the sizes and shapes of mineral grains and other constituents in a rock, and how these sizes and shapes relate to each other. Such factors are controlled by the process which formed the rock.
How do you read an igneous rock classification chart?
When identifying an igneous rock its chemical composition can be determined by its color?
Color is often an indicator of the composition of a rock or mineral and can be effectively used to identify the composition of most igneous rocks. Light colors, including white, light gray, tan and pink, indicate a felsic composition. Felsic compositions are rich in silica (SiO2).