Types Of Rocks And Minerals

There are so many types of rocks and minerals that grace the earth’s surface. While rocks can be classified into three major types, minerals on the other hand have more than 1000 different types and more are still being discovered each day. This article shall present the different types of rocks and minerals beginning from rocks.

Different types of rocks and minerals – Igneous rocks

There are so many features of igneous rocks. Igneous rocks are formed from the cooling and solidification of magma. Those that are very light have more acid and contain more than 60 percent silica. Those that are darker have lesser volume of ferro magnesian minerals and are more basic. Therefore, igneous rocks can be subdivided into basic, intermediate, and acidic types. Basic igneous rocks contain about 50 percent silica, intermediate ones contain about 60 percent silica, while acidic igneous rocks contain more than 65 percent silica. An intrusive igneous rock is formed when magma gradually cools below the earth’s surface. On the other hand, an extrusive igneous rock is formed when magma turns to lava (reaches its highest melting point), cools and quickly solidifies. The state of the rock during formation result to different sizes of the formed rock. Extrusive igneous rocks are usually less coarse-grained than extrusive. Examples of igneous rocks include Obsidian, Rhyolite, and Granite. Granites are the most

common types of igneous rocks.

Different types of rocks and minerals – Sedimentary rocks

These are formed when pebbles and sand layers are compressed to transform into a rock. Limestone is the main constituent of sedimentary rocks as a result of the fossilization of organisms. There are also different sizes of the sedimentary rock depending on the formation conditions. The fine sizes can only be seen with a microscope while the medium sizes are seen using hand lenses, and the coarse types can easily be seen with the eyes.

There are three categories of the sedimentary rock: biogenic, detrical, and chemical sedimentary rocks. Biogenic rocks are made of shell and fossil fragments. Detrital rocks are made up of other preexisting rock particles, while chemical rocks include rock formed by the precipitation of minerals. Common types of sedimentary rocks include limestone, shale, and sandstone.

Types of rocks and minerals – Metamorphic rocks

These are usually formed as a result of pressure or heat, but may not reach melting point. The texture of the rock largely depends on whether they were formed by heat or a combination of heat and pressure.

The more temperature and pressure they are subjected to the bigger their grains. Some good examples of these types of rocks include granulite, marble, and slate.

Type of Minerals

There have been more than 2000 minerals identified and more are discovered each year. But not all of them are commonly found in the earth’s surface. They chemistry means they can be subdivided into different categories. The following are therefore classification of minerals found on the earth’s crust:

Types of rocks and minerals – Silicate minerals

Silicate minerals

These are the widely known types of minerals on earth. Their main composition is oxygen and silica, and majority of them are formed when rocks melt and cool down either beneath the earth or at the surface of the earth.

Types of rocks and minerals – Non-silicate minerals

These groups are formed during water evaporation leaving crystals of mineral behind. They are equally formed after other minerals decompose or when molten rock cools.