Igneous rock sources are primarily magmas, which are molten or partially molten material that is found beneath the Earth's surface. Magmas are composed of minerals and gases, and they are formed when rocks melt due to high temperatures and pressures. Magmas can be further classified into two categories: intrusive and extrusive. Intrusive magmas form plutonic rocks, while extrusive magmas form volcanic rocks. Igneous rocks are formed when magmas cool and solidify.