Earth Science 110 Igneous Rocks

Igneous rocks can form______ or ______ Earth's surface

below; above

Intruisve or _____ igneous rocks form due to ______cooling beneath the surface?

Plutonic, slow

Plutonic igneous rocks have _____ minerals that are _____ to see.

large; easy

Extrusive or _____ igneous rocks form due to ______ cooling at or above the earth's surface

volcanic; fast

____ igneous rocks are composed of dark-colored, ____ density minerals.

mafic; higher

________ igneous rocks are composed of _______, low density minerals.

Felsic, light-colored

Pumice is an example of _____ rock?

Igneous

What is one of the most common igneous rocks?

Granite

Igneous rocks form when molten materials ______ and ______.

Cools, hardens

Where do igneous rocks form?

They may form either below or above earth's surface

What type of rocks make up most of the rocks on Earth?

Igneous

Igneous rocks are called plutonic when they _______.

Cool and solidify beneath the surface. Since they form within the earth, cooling occurs slowly

Intrusive/plutonic igneous rocks have _____ mineral crystals that are easy to see.

Large

Igneous rocks are called volcanic when they ______.

Form above the surface. These rocks cool much more rapidly and therefore have smaller crystals.

What is an obsidian rock?

An obsidian rock is a type of volcanic igneous rocks that cooled so rapidly, crystals do not develop at all. They form a type of glass.

What is the most common type of extrusive/volcanic igneous rock?

Basalt

How are igneous rocks classified?

Igneous rocks are classified by how and where they formed. (I.e. Plutonic/volcanic, mineral composition)

What are the four types of mineral compositions of igneous rocks?

Fensic, intermediate, mafic, or ultramafic.

What are felsic rocks made of?

Light colored, low density minerals

What are mafic rocks made of?

Dark-colored, higher-density minerals such as olivine and pyroxene

What are intermediate rocks made of?

Intermediate rocks have compositions between felsic and mafic

What are ultramafic rocks made of?

Contain more than 90% mafic minerals and have very few light, felsic minerals in them

Extrusive or volcanic

A type of igneous rock that forms above the earth's surface

Felsic

igneous rock composition that is mostly made of light minerals such as quartz and feldspar