Chapter 3 Apply

Question 1

Describe how one could use the Mohns scale to determine a mineral’s hardness.

Answer 1

Scratching the sample with various test objects (fingernail, copper penny, steel knife,etc.); the hardness can be determined by which objects are able to scratch the sample.

Question 2

Why are mineralogy and petrology branches of geology?

Answer 2

Mineralogy and petrology are the study of specific aspects of the earth and are therefore branches of geology.

Question 3

Can metamorphic rocks form from intrusive or extrusive rocks? Explain.

Answer 3

Intrusive and extrusive rocks are the two types of igneous rocks.

Metamorphic rocks can form from any type of igneous rocks.

Question 4

Explain how the different processes that form coarse-grained, fine-grained, and mixed-textured igeous rocks affect the textures of these rocks.

Answer 4

The chief condition affecting an igneous rock’s texture is the rate at which the magma cools; generally magma that cools more slowly will have larger crystals.

Coarse-grained igneous rocks form when magma cools quickly, often during volcanic eruptions, forming smaller crystals.

Fine-grained igneous rocks form when magma cools quickly, often during volcanic eruptions, forming smaller crystals.

Mixed-textured rocks form when magma cools first slowly and then quickly, causing both large and small grains to develop; these rocks are thought to form when magma begins to cool beneath the surface but is ejected from the earth before it completely hardens.