Students learn to classify and group rocks according to their observable properties such as color, shape, hardness, and texture. Rocks record details of the Earth's formation and can be associated with different environments based on their composition and origin as sedimentary, igneous, or metamorphic rocks. Examples of rocks commonly found in buildings and cities include different types of sedimentary rocks, igneous rocks, and metamorphic rocks, even if they did not originally form in that location.