What are the characteristics of mafic rocks?

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.

What are the characteristics of felsic rocks?

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.

What are the characteristics of ultramafic rocks?

Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous and meta-igneous rocks with a very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are composed of usually greater than 90% mafic minerals (dark colored, high magnesium …

What are the characteristics of mafic rocks and lava flows?

They are thick and gooey and resist flowing. Their high volatile content makes them potentially highly explosive. Because mafic lava is low viscosity, when it erupts from a volcano it flows downslope away from the vent, gradually cooling and crystallizing.

What texture are mafic rocks?

Mafic

What are the three main compositions of igneous rocks?

Composition of igneous rocks reflects the chemistry of the original magma.

• Mafic rocks are richer in Mg, Fe, and Ca. …
• Felsic rocks are richer in K, Na, Al and Si, and, compared to mafic rocks, are lighter in color as well as density.
• Intermediate compositions lie between these two end members.

What are the 4 textures and compositions of igneous rocks?

Igneous rocks can be divided into four categories based on their chemical composition: felsic, intermediate, mafic, and ultramafic.

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 are the characteristic of igneous rock?

Answer

• 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.
• May be fine-grained or glassy (extrusive)

What is a felsic composition?

Felsic rocks are mostly feldspar (especially K-feldspar), at least 10% quartz, and less than 15% mafic minerals (biotite, hornblende).

What are mafic igneous rocks?

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.

What is the difference between the composition of felsic and mafic igneous rocks?

The main difference between Mafic and Felsic rocks are the silica content present. Since igneous rocks are characterised by silica content in them, mafic is the one with less silica content (approx. 45-55%) while felsic is the one with a greater silica content (approx. 70-90%).

What is the difference between felsic and mafic rocks?

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. 6. Mafic rocks are darker in color than felsic rocks.

Where are mafic rocks formed?

mid-ocean ridge seafloor spreading centers

INTRODUCTION. Mafic rocks that constitute the igneous oceanic crust are created at mid-ocean ridge seafloor spreading centers as a byproduct of partial melt from upwelling mantle.

Which of the following characteristics can indicate the composition felsic or mafic of an igneous or volcanic rock?

Felsic minerals (quartz, K feldspar, etc) are light colored while mafic minerals (hornblende, pyroxenes) are normally dark colored.

What does mafic mean?

Definition of mafic

: of, relating to, or being a group of usually dark-colored minerals rich in magnesium and iron.

What two components are responsible for the dark color of mafic rock?

Mafic describes magma or igneous rock that is rich in magnesium and iron and is generally dark in color. mineral olivine are responsible for the dark color of mafic rock.

Are mafic rocks magnetic?

Magnetic susceptibility measurements performed on rock outcrops and hand samples from the study area also reveal lower magnetic susceptibilities for sedimentary and felsic intrusive rocks, moderate susceptibility values for metamorphic, felsic extrusive, and intermediate igneous rocks, and higher susceptibility values …

Are mafic rocks intrusive or extrusive?

Basalt and gabbro are the extrusive and intrusive names for mafic igneous rocks, and peridotite is ultramafic, with komatiite as the fine-grained extrusive equivalent.

Is mafic acidic?

Just a comment to add the modern terminology: we now use “mafic” for “basic” and “felsic” for “acid”. These terms are based on modal minerals, ferromagnesian for the first (hence ma-ferric), feldspar and quartz for the second (hence fel-si).

What is the best characterization of a fine grained igneous rock?

Characteristics: Fine-grained – The grains are too fine to identify the minerals without a microscope. Some fine‑grained igneous rocks have rectangular crystals in them. Very hard!

How is magma formed?

Magma forms from partial melting of mantle rocks. As the rocks move upward (or have water added to them), they start to melt a little bit. These little blebs of melt migrate upward and coalesce into larger volumes that continue to move upward. They may collect in a magma chamber or they may just come straight up.