A mineral is a naturally occuring, homogeneous, solid with a crystalline atomic structure. Crystallinity implies that a mineral has a definite and limited range of composition, and that the composition is expressible as a chemical formula. Some definitions of minerals give them as inorganic materials, however both diamonds and graphite are considered minerals, and both are primarily comprised of carbon, which would make them organic. So this leads me, as an engineer, to believe that mineralogists do not have a good, precise definition of a mineral, but rather a loose definition. The definition above, is the most inclusive and would include all substances currently described as minerals. The key items that make something a mineral are occurring naturally, and the definite crystal structure, that is expressible as a chemical formula. Rocks that do not meet this criteria are referred to as amorphis - not having a definite structure or expressible as a chemical formula. Some elements that occur naturally and are minerals are arsenic, bismuth, platinum, gold, silver, copper, and sulphur.

THE DEFINITION OF ORGANIC: Organic chemistry is the study of those substances containing carbon in combination with hydrogen (H), and a few other non metals, namely oxygen (O), nitrogen (N), sulfur (S) and the halogens (F2, Cl2, Br2, and I2).

Fluorite is usually found in a very pure state, is typically transparent, but can be greenish, yellowish. bluish, red, brown or white colored. It can be found with limestone deposits, dolomite and granite. It is a fairly commonly occurring mineral. It is used widely in the manufacture of steel, glass, enamel wares, chemicals (hydroflouric acid, and is used in many metallurgical processes. It's crystal structure is hexoctahedral. It has a SG of 3 - 3.2 and a hardness of 4.

Another unusual property of fluorite is that it is strongly fluorescent and phosphorescent when heated or exposed to electrical discharge. The specimin in the photo came from the Ontario Province of Canada.