1. Meaning of Rock
  2. The Process of Rock Formation
  3. Rock Minerals
  4. Types of Rock

Meaning of Rock

Rock is defined as any mineral material of the earth. Rock can also be defined as the aggregate of minerals made up of hard and soft materials like stone, sand, etc. Rock constitutes a significant part of the earth's crust. The earth's crust consists of rocks which are the combination of different mineral elements such as silica which contains silicon and oxygen. Rocks are aggregates (mixtures) of minerals.  

The Process of Rock Formation

Rocks are formed as a result of volcanic eruptions from earth’s crust. During the volcanic eruption the molten material or magma may remain within or escape to the surface . The magma or lava subsequently cools and solidifies to form glassy crystalline textured mass. In Nigeria rocks are found in Benue, Bauchi, Zaria, Plateau, Ilorin, Ondo, Ado-Ekiti, Abakiliki and Ogoja in Cross River State, etc. Some of the magma may cool before reaching the surface of the earth thus forming plutonic rocks (intrusive rocks) while some may reach the surface to form volcanic rocks (extrusive rocks) Examples of plutonic (intrusive) rocks are granite, diorite, gabbro, etc. Examples of volcanic (extrusive) rocks are basalt, andesite, obsidian, pumice, rhyolite, scoria and tuff. Rapid cooling gives rise to fine grained rocks,while slow cooling gives rise to larger grained rocks.  

Rock Minerals

Rock contains primary and secondary minerals, namely;

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