This video from MooMooMath and Science explains igneous rocks, their formation from molten rock, and the differences between intrusive and extrusive types. It covers the characteristics of these rocks, such as crystal size and texture, and introduces the classification of igneous rocks into mafic and felsic based on silica content and color. The video concludes with additional resources for further learning.

What is the origin of the name 'igneous'?

• It is derived from a Greek word for fire.

• It is derived from an Egyptian word for air.

• It is derived from a Latin word for water.

• It is derived from a Roman word for earth.

What is the primary difference between intrusive and extrusive igneous rocks?

• Intrusive rocks form inside the earth, while extrusive rocks form on the surface.

• Intrusive rocks are made of lava, while extrusive rocks are made of magma.

• Intrusive rocks cool quickly, while extrusive rocks cool slowly.

• Intrusive rocks form on the surface, while extrusive rocks form inside the earth.

How do extrusive igneous rocks typically cool?

• Moderately

• Very slowly

• Quickly

• Not at all

What is a common characteristic of extrusive igneous rocks?

• They have large crystals.

• They have a coarse texture.

• They may have air bubbles.

• They are always dark in color.

What is the typical texture of intrusive igneous rocks?

• Fine

• Coarse

• Glassy

• Smooth

What is the size of crystals in intrusive igneous rocks?

• Larger than 1 millimeter

• No crystals at all

• Smaller than 1 millimeter

• Microscopic

What percentage of silica is considered mafic in igneous rocks?

• 0 to 45 percent

• 45 to 65 percent

• 85 to 100 percent

• 65 to 85 percent

What color are mafic rocks typically?

• Light

• Dark

• Red

• Green

What does the term 'felsic' indicate about an igneous rock?

• It contains a high percentage of iron.

• It contains a high percentage of silica.

• It is dark in color.

• It is formed from lava.

What minerals are indicated by the term 'mafic'?

• Silica and feldspar

• Magnesium and iron

• Sodium and aluminum

• Calcium and potassium