Mineral Case

If I was a mineralogist trying to identify a mineral that I wasn't familiar with I would examine the physical properties of the mineral. The three main characteristics I would look at are "optical properties, crystal shape or habit, mineral strength" when determining the classification of a mineral.(Lutgens & Tarbuck, 2011).

Using optical properties you want to look for the minerals "luster, ability to transmit light, color, and streak" (Lutgens & Tarbuck, 2011, p. 28). A minerals luster is "the appearance or quality of light reflected from the surface of a mineral" (Lutgens & Tarbuck, 2011, p. 29). Determining a minerals luster can help to classify the mineral. Another way to classify a mineral is whether or not it has the ability to transmit light through the mineral. Color can help to determine a mineral, but be careful not to be fooled. Several minerals can be found in different colors. This is property I would find to be the least useful in determining a mineral. A streak is the "color of the mark a mineral makes when you rub it against a piece of unglazed porcelain" (Lutgens & Tarbuck, 2011, p. 29). While the color of a mineral can vary, its streak is usually the same color. You must make sure that the mineral is softer than surface you are rubbing it against or no streak will appear.

A minerals crystal shape or habit is another way to classify a mineral. Many mineral have a constant shape, knowing and comparing these shapes is helpful in determining a mineral.

Testing a minerals strength can also help to classify a mineral. Determining how hard a mineral is, or how it scratches, fractures, or bends is testing its strength. Minerals have different strengths, and react differently under pressure, determining this can help to classify a mineral.

All of these will help you in classifying a mineral. I would recommend not basing your finding on doing only one test. If you think you know what the mineral is, do additional test that will help you determine the classification.

References

Lutgens, F. K., & Tarbuck, E. J. (2011). Foundations of Earth Science (6th ed.). Upper Saddle River, NJ: Prentice Hall.