Mineralogists use a very specific definition of a mineral.
Minerals must be created by nature. If they are made by human
intervention they are referred to as "man-made." Minerals are inorganic,
meaning that they are made from nonliving matter.
Minerals have an internal, crystalline
structure. Molecules that make up the mineral are arranged in a set
pattern. This crystalline structure is sometimes reflected as a crystal,
if the mineral is given room to grow. However, even organic substances
can grow crystals. For example, sugar which is organic, can make sugar
crystals commonly called "rock candy." So not all crystals are
Minerals have a definite chemical
composition. Minerals are always composed of the same elements.
Minerals are rarely composed of one element. These native minerals,
include gold, silver, copper, and sulfur. However, most minerals are
made of compounds (combinations of two or more different elements). For
example, halite (NaCl) or table salt, is always composed of only
two elements, sodium (Na), and chlorine (Cl). Geologists classify
minerals into chemical families based on their compositions.
The crystal structure of halite.