The following is a concise list of what it means for something to be designated as a mineral or a rock.
- A mineral is a naturally occurring, inorganic solid with a definite chemical composition and a crystalline structure.
- A rock is an aggregate of one or more minerals. (A rock may also include organic remains.)
- Some rocks are predominantly composed of just one mineral. For example, limestone is a sedimentary rock composed almost entirely of the mineral calcite.
- Other rocks contain many minerals, and the specific minerals in a rock can vary widely.
- Some minerals, like quartz, mica or feldspar are common, while others have been found in only one or two locations worldwide.
- 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.
- Commercially valuable minerals and rocks are referred to as industrial minerals.