Minerals

'''Minerals''' are natural occurring, inorganic materials of consistent chemical composition. Usually their atoms are arranged in a definite crystal structure. Most [[Gemstones|gemstones]] are minerals. Since they have a uniform chemical composition each mineral has consistent set of physical and optical properties.

==Classification==
Mineralogists and Gemologists classify minerals by 'group', 'species', and 'variety'.

===Group===
Groups can contain two or more minerals with similar properties and structure but slightly differ in chemical properties. For example when one chemical element replaces another in the same formula.

===Species===
Each specific member of a 'group' is a 'species' which can then contain numerous 'varieties'. All stones in a 'species' have the same crystal structure and chemical composition and differ only in color. 

===Variety===
Color variation in the different varieties of a species are caused by the presence of minute impurities. 

==Mineraloids==
Material found in the earth that originated from living organisms such as amber and jet are called mineraloids.

==Rocks==
Rocks are a combination of two or more minerals. Gemstones such as lapis lazuli which is a mixture of lazurite, calcite and sometimes pyrite are classified as rocks.

[[Category:Gemology]]