Most of them are not known to professional mineral collectors, because they are rare, have no economic purpose, and for the most part do not make good specimens. The best way to define a rock is to say that it is an indefinite mixture of naturally occurring substances, mainly minerals. Its composition may vary in containment of minerals and organic substances, and are never exact. They can range from tiny microscopic grains of minerals or organic substances to coarse agglomerates of different minerals, where the individual minerals are easily discernible. They may range in size from tiny pebbles to huge mountains.
Rocks make up the earth's crust .
In general, the only people interested in rocks are geologists and paleontologist who are interested in the scientific nature and dating of the rocks. Different mineral deposits can be found in related rock formations, providing use by estimating what minerals rock formations may contain. Although a few people collect rocks , the amount of people collecting minerals is much greater. Advertise on this page This page is open to sponsor.