What are Rocks?
Rocks are combinations of one or more minerals. Rocks are made up of minerals like: quartz, calcite, feldspars, and micas. Most rocks are made up of from more than one mineral but rocks can also be made up of just one mineral. It's important to remember that minerals are not rocks.
What are Minerals?
Minerals are substances (elements) or combination of substances. Minerals are the raw materials of rocks. Rock types are characterized by the types of minerals present in their relative proportions, and the processes by which the rocks were formed. Of these processes, heat, pressure, and time are the most important. Minerals are divided into two different groups based on their chemical components: silicate minerals and non-silicate minerals.
Silicate minerals form when molten rock cools. Silica and oxygen are the main components of silicate minerals. Mica, feldspar and quartz are all examples of silicate minerals.
Non-silicate minerals form one of three ways: When magma cools, when water evaporates, or when other minerals decompose. Carbonates, sulfates and sulfides are examples of non-silicate minerals.
The Rock Cycle
Rocks do not last forever; the weather, running water, and ice wear them down. All kinds of rocks become sediment. Sediment is sand, silt, or clay. As the sediment is buried it is compressed and material dissolved in water cements it together to make it into sedimentary rock. If a great amount of pressure is exerted on the sedimentary rock, or it is heated, it may turn into a metamorphic rock. If rocks are buried deep enough, they melt. When the rock material is molten, it is called a magma. If the magma moves upward toward the surface it cools and crystallizes to form igneous rocks. This whole process is called the Rock Cycle.
To practice identifying rocks play this game!
