The following is a concise list of what it means for something to be designated as a mineral or a rock.

  1. A mineral is a naturally occurring, inorganic solid with a definite chemical composition and a crystalline structure.
  2. A rock is an aggregate of one or more minerals. (A rock may also include organic remains.)
  3. Some rocks are predominantly composed of just one mineral. For example, limestone is a sedimentary rock composed almost entirely of the mineral calcite.
  4. Other rocks contain many minerals, and the specific minerals in a rock can vary widely.
  5. Some minerals, like quartz, mica or feldspar are common, while others have been found in only one or two locations worldwide.
  6. Over half of the mineral species known are so rare that they have only been found in a handful of samples, and many are known from only one or two small grains.
  7. Commercially valuable minerals and rocks are referred to as industrial minerals.