# The earth’s crust is made up of various types of rocks. # Rock- Any natural mass of mineral matter that makes up the earth’s crust. # There are three major types of rocks- Igneous rocks-when the molten magma cools; it solidifies to become igneous rock. # Sedimentary rocks- igneous rocks are broken down into small particles that are transported and deposited to form sedimentary rocks. # Metamorphic rocks- When the igneous and sedimentary rocks are subjected to heat and pressure, they change into metamorphic rocks. # Rocks are made up of different minerals. Minerals- are naturally occurring substances which have certain physical properties and definite chemical composition. # Minerals are very important to humankind. Some are used as fuels. For example, coal, natural gas and petroleum. They are also used in industries – iron, aluminium, gold, uranium, etc., in medicine, in fertilisers, etc.