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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).




The Mineral, Limonite is a Iron Ore mineral and accounts for a small percentage of the iron mined. Limonite is crystaline to amorphous, has a hardness of 1 to 5.5, SG of 3.4 to 4, and is yellowish, brown or black. Limonite is the result of decomposition of iron minerals, where water, carbon dioxide, humus acid and oxygen react with the minerals and gradually transform them into limonite. It is very common, and can be found with other iron minerals such as pyrite, hematite, etc.. In addition to a source for iron, limonite is used as paint pigment and in some ceramics (for color)