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).

Dolomite is a carbonate mineral.This large specimin is from a local mine. Dolomite is calcium magnesium carbonate, a common sedimentary rock that is transformed into a mineral mineral. Dolomite is also called dolomitic limestone. The amount of calcium and magnesium in most specimens is equal, but occasionally one element may have a slightly greater presence than the other. Small amounts of iron and manganese are sometimes also present.

Dolomite is used to make magnesia, which is used in medical applications, used as an ornamental and structural stone, in metallurgy for extracting certain metals from their ores, and is used in the chemical industry in the preparation of magnesium salts.


Color is often pink or pinkish and can be colorless, white, yellow, gray or even brown or black when iron is present in the crystal. Luster is pearly to vitreous to dull.
Transparency crystals are transparent to translucent.
Cleavage is perfect in three directions forming rhombohedrons.
Hardness is 3.5-4
Specific Gravity is 2.86 (average)
Streak is white.
Other Characteristics: Unlike calcite, effervesces weakly with warm acid or when first powdered with cold HCl.
Dolomite is found in Midwestern quarries of the USA; Ontario, Canada; Switzerland; Spain and in Mexico, along with many other places in the world.
Best Field Indicators are typical pink color, crystal habit, hardness, slow reaction to acid, density and luster.

The photo at left is White Dolomite, from California.