They are formed by the cooling of magma.
These rocks are formed by the solidification of lava.
They are called igneous rocks because they are created by intense heat.
They can form on or below the Earth's surface, either by crystallization or not.
Magma is formed by the partial melting of rocks in the Earth's crust or mantle.
Magma is usually formed for three reasons: an increase in temperature, a decrease in pressure, and a change in composition.
There are more than 700 types of igneous rocks.
Most of these are found below the Earth's surface.
Acid igneous rocks are less dense and less colorful.
They have a higher silica content (usually 65-85%).
They are mainly composed of light-colored minerals such as quartz and feldspar. Therefore, they are light in color.
Ex: Granite
Basic igneous rocks are dense and dark in color.
They are low in silica (usually 45-60%) and high in magnesium and iron.
They are mainly composed of dark-colored minerals such as pyroxene and olivine. Therefore, they are dark in color.
Ex: Basalt
