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).

Turquois is a secondary mineral, often associated with limonite, quartz, feldspar or kaolin. It occurs in veins, stalactic masses and as coatings or crusts, and grains or rounded pebbles. It has a hardness of 6, SG of 2.6 to 2.8, and is various shades of blue and green. It is used as a gem mineral. The specimen in the photo is from a vein of turquois found in New Mexico. The color of turquois will fade with time.

Vein turquois generally occurs in thin laminate sections, similar to those in the photo of turquois ore. It is very popular with the American Indians, and peoples of the southwest and western US.