Earth Science A - NW 4

What is the difference in appearance between an extrusive igneous rock and an intrusive igneous rock?

Extrusive is made from lava and intrusive is made from magma.

What is the biggest factor that controls whether a rock is coarse or fine-grained?

The speed of cooling

Describe how felsic igneous rocks differ in appearance from mafic igneous rocks.

Felsic-Light colored and rich in quartz and feldspar.

Mafic-Dark colored and rich in magnesium and iron.

What is the difference between magma and lava?

Magma is under the surface, lava is on the surface

How could you determine if a rock formed from magma or from lava? Be specific.

Magma-Formed inside the earth, takes longer to cool—>larger crystals

Lava-Formed on the surface, shorter cooling time—>smaller crystals/no crystals in some cases

How are granite and rhyolite similar? How are they different?

Granite and Rhyolite are Felsic rocks, but Rhyolite is coarse-grained intrusive, and granite is fine-grained extrusive.

How are basalt and gabbro similar? How are they different?

They are both Mafic rocks, but Basalt is Fine-grained extrusive, and Gabbro is Coarse-grained intrusive.

How are diorite and andesite similar? How are they different?

They are Intermediate rocks, but Diorite is Intrusive Coarse-grained and Andesite is Extrusive Fine-Grained.

Coarse grained, Intrusive, Felsic

Granite

Fine grained, Extrusive, Felsic

Rhyolite

Coarse grained, Intrusive, Intermediate

Diorite

Fine grained, Extrusive, Intermediate

Andesite

Coarse grained, Intrusive, Mafic

Gabbro

Fine grained, Extrusive, Mafic

Basalt

Glassy, Extrusive,

Obsidian

Glassy/Vesicular, Extrusive

Pumice