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Chemical Properties of Minerals


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The chemical properties of minerals mainly reflect the chemical properties of the atoms present in each. However, even here these properties depend on the way the atoms are bound in the mineral's crystal structure. Let us examine the property known as solubility — the ability of a mineral to dissolve in a liquid, like salt and water.

Nearly all minerals are soluble in water. But most dissolve to such a limited extent as to go almost unnoticed. A liquid is called a solvent when it's action on a solid substance is to break apart the atoms of the crystal structure, thus dissolving it.

With some minerals, not all the atoms in the crystal structure are taken into solution. The two specimens at the lower left illustrate this phenomenon for the mineral muscovite. Fresh crystals in one specimen contrast with the other, to its right, which look somewhat faded. If the fresh looking sample were subjected to running water, potassium atoms originally present in the layered structure would dissolve, and the muscovite would gradually change from a mica to a clay minerals. Such is the mineral illite, the faded-looking sample.
In the series of mineral groups displayed on the right side of this case, different specimens show variations in chemical properties. The top group represents the range of temperatures at which the minerals will melt or change to a liquid. The melting point is also known as the fusing temperature.

Minerals composed of atoms that are not tightly bonded within the crystal structure will melt at relatively low temperatures. However, much heat may be needed to break the chemical bonds of other minerals. The mineral quartz, for example, will only melt above 1,610 degrees Celsius, or 2,930 degrees Fahrenheit. The next group of minerals are not found in areas of high rainfall or high humidity because these minerals dissolve easily in water. Thus, a desert region, such as Death Valley, would be an ideal place for these minerals to form.

Water is not the only