These tools use the physical properties of the mineral to give you clues to match the mineral by use of a mineral identification key. The physical properties include color, streak, luster, hardness, crystal form, cleavage, fracture, specific gravity, and other unique properties. We will take a look at each of these in turn. Color is the first thing a person will notice about a mineral. It is important to not overly rely on color as a diagnostic tool.
Color can be the most beneficial in identification, and also the most unreliable of the properties.
Some minerals, such as calcite have many different colors. These color changes are the result of impurities in the minerals composition. A minerals streak is usually more reliable than color. Streak is the color given off by a pulverized mineral. Generally this is achieved by rubbing the mineral on a porcelain plate or other surface.