When a child picks up a rock and skips it on the water, it is nothing more than a small rock. A child skipping a rock makes a pleasant picture for the world to see. After all, one small rock is not very important. Small rocks, whole or ground, grouped together are called aggregates. These aggregates form the basis of modern living. They are an integral part of the foundations of homes and offices. Modern roads and highways are possible because of aggregates. Even the garden patio would not be the same without them.

Rocks and sand are mined in quarries to provide many of the building materials in use today. Granite countertops are a good example. When mined, this material does not form natural slabs. Large pieces are cut out of granite deposits. When an area has other rock types, small granite pieces are left behind. These pieces are gathered up to become part of the aggregate used as modern building materials rather than being tossed aside as useless.