Lab #4: Igneous Rocks Flashcards
How is Igneous rock formed?
Over time, magma cools and solidifies(Crystallization). This process, called crystalization, may occur either beneath the surface or, following a volcanic eruption, at the surface.
What is magma and how is it formed?
Magma is the parent matierial for igneous rock. It is formed by partial melting that occurs at various levels within the earth’s crust and upper mantle.
What happens to magma after it is formed in the crust and upper mantle?
The magma buoyantly rises towards the surface because it is less dense than the surrounding rocks.
What controls the texture of igneous rock?
The texture of an igneous rock is controlled by the rate that the magma cools.
What controls the composition of igneous rocks?
The composition is controlled by the mineralogy, or chemistry, of the magma.
What are plutonic rocks.
Plutonic rocks (also called intrusive rocks) are formed when mama crystallizes at depth.
What are extrusive igneous rocks?
Molten rock that solidifies at the surface.
What is igneous rock mostly composed of?
It is mainly composed of silicate materials. Silicon and oxygen are by far the most abundant constituents of igneous rocks.
What are ferromagnesium silicates?
The “dark” silicates that are rich in iron and/or magnesium and comparatively low in silica. Common ferromagnesium silicates include olivine, pyroxene, amphibole, and biotite.
What are nonferromagnesium silicates?
“light” silicates contain greater amounts of potassium, sodium, and calcium rather than iron or magnesium. Quartz, muscovite, and the feldspars, are richer in silica than the dark silicates.
What are granitic compositions?
Rocks that are composed of light colored silicates, like quartz and potassium. These rocks are felsic, which means it is derived from feldspar and silica.
What is the % composition of typical granitic compositions?
10 % dark silicate material, usually biotite mica and amphibole.
70% Silica.
What are basaltic
