Geology Igneous Rocks Chapter 4

What is the difference between felsic, intermediate, mafic, and ultramafic

- Felsic- refers to a predominance of the light-colored (felsic) minerals feldspar and silica in the form of quartz. - Intermediate - It usually contains roughly-equal amounts of light and dark minerals - Mafic - refers to an abundance of ferromagnesian minerals and is mostly made of dark minerals. - Ultramafic - refers to the extremely mafic rocks composed of mostly olivine and some pyroxene which have even more magnesium and iron and even less silica. Rare on surface.

Where are igneous rocks formed?

Either at volcanoes on the surface of the Earth or while the melted rock is still inside the crust

What are the two major types of igneous rocks on the basis of texture?

Extrusive and intrusive

What is an igneous rock?

Rocks that are formed from liquid rock, ex. from volcanic processes

What factors control the size of crystals ("grain size") in igneous rocks?

The cooling rate of the molten rock or magma

What are the main properties/components of magma?

melt, solids, and volatiles