What Makes Up Rocks?

Basically, a rock is a solid mass of one or more minerals. It can also be made up of geological materials such as fossils or inorganic non-mineral solids. The type of material that makes up a rock can tell us a lot about the past of the Earth.

Rocks can be broken down into three major categories: igneous, sedimentary, and metamorphic. Each of these rocks is composed of different types of minerals. Some rocks are formed of only one mineral.

Gneiss is a very hard and tough rock, usually made up of quartz and feldspar. However, gneiss can contain other minerals such as garnet. It can also be dark in color. The top and bottom layers of schist are usually made of mica.

In contrast, marble is a soft and coarse grained rock. It usually consists of a white to gray substance that may be streaked or patchy in color.

Sedimentary rock is formed from material that has been deposited by water. It is compacted by weight. The particles of the sediment include silt, clay, and sand. When a sedimentary rock is exposed to the air, it wears away. During this process, small fragments are transported to a new location. This is known as the rock cycle.

If the rock is exposed to a high temperature, new minerals will form. Some rocks can even become glassy. Some rocks can be dissolved in water and then cement together to form metamorphic rock.