Week 5

Oct 31, 2015
1 min read

This week’s lectures discussed rock types. The three major rock classes are based on how they were formed.

Igneous Rocks

Igneous rocks are the ones that were superheated and originally liquid. They come from near the center of the Earth.

There are two basic types of igneous rocks. There are the rocks that make it to the surface (extrusive) and the ones that are stuck in the crust just below the surface (intrusive).

These igneous types have all hardened after being molten rock.

Metamorphic Rocks

This rock type is created by heat and/or pressure. Even though heat is involved, they didn't start off as molten rock.

Some examples are marble, jade, slate, and gneiss.

Because pressure and heat are involved, these rock types are usually found deep beneath the surface. They are also found near fault lines where plates push against each other.

Sedimentary Rocks

Sedimentary rock types are created when sediment compresses. Some sedimentary rocks, such as chert and certain limestones, are formed from chemical precipitation, which is the formation of a solid from a solution.

Examples of sedimentary rock include sandstone, amber, anthracite, and limestone.

In addition to the lectures on this topic, this week also included an extremely interesting lab session which helped us understand the material in a better way.

The lab required us to observe several samples of minerals and to describe their properties like color, luster, chemical composition and hardness.

(The following images are my own snapshots)