Igneous Rocks

Rocks are groups of minerals bound together in some way. There are three major groups of rocks:

• igneous - rocks formed from molten (melted) rock material
• sedimentary - formed from the hardening and cementing of sediments
• metamorphic - rocks changed by heat, pressure and chemicals

Why are rocks important? They are valuable sources of useable resources. If an object doesn't come from a plant or animal, there's a good chance it came from the ground. Earth's crust is a resource for numerous gems, metals, building supplies, energy, and other important materials. They also give us clues to the past events and processes that have shaped the planet on which we live. And, these past events may provide hints at what lies ahead for us in the future.