Igneous rocks are formed when magma or lava cools and solidifies. Magma is molten rock that is found beneath the Earth's surface, while lava is molten rock that has erupted onto the Earth's surface. Igneous rocks can be classified into two main types: plutonic and volcanic. Plutonic igneous rocks are formed when magma cools and solidifies slowly beneath the Earth's surface. These rocks are generally coarse-grained and have a crystalline texture. Volcanic igneous rocks are formed when lava cools and solidifies quickly at the Earth's surface. These rocks are generally fine-grained and have a glassy or porphyritic texture.
Sedimentary rocks are formed when sediments accumulate and are compacted and cemented together. Sediments are bits of rock, mineral, or organic matter that are transported by wind, water, or ice. Sedimentary rocks can be classified into three main types: clastic, chemical, and organic. Clastic sedimentary rocks are formed when sediments are compacted and cemented together. Chemical sedimentary rocks are formed when minerals precipitate out of solution in water. Organic sedimentary rocks are formed when the remains of plants and animals are compacted and cemented together.
Metamorphic rocks are formed when existing rocks are changed by heat, pressure, and/or chemical reactions. Metamorphic rocks can be formed from any type of rock, but they are most commonly formed from igneous and sedimentary rocks. Metamorphic rocks can be classified into two main types: foliated and non-foliated. Foliated metamorphic rocks have a layered or banded appearance, while non-foliated metamorphic rocks do not have a layered or banded appearance.