Igneous Rock Quiz2

What is the origin of the name 'igneous'?

• Derived from a French word for 'molten'

• Derived from a Greek word for 'fire'

Where may igneous rocks form from magma?

• In the water

• Inside the earth

What determines the texture of igneous rocks?

• The rate of cooling

• The location of formation

What type of texture do extrusive rocks have?

• Coarse

• Fine

What is the size of crystals in intrusive rocks?

• One millimeter or larger

• No crystals at all

What percentage of silica makes a rock felsic?

• 65% or greater

• 0 to 45%

What minerals make up mafic rocks?

• Magnesium and iron

• Quartz and feldspar

What is the hardness range of obsidian?

• Between 5 and 6

• Between 6 and 7

Which rock is described as having a very fine texture and can float in water?

• Granite

• Rhyolite