Answer: Minerals possess a number of properties that are used as an aid in their identification. These are listed below with a brief description:
Explanation: Color--The color of the specimen as it appears to the naked eye under normal lighting conditions. Some minerals such as gold will only appear as one color, but due to impurities and Crystal Light distortion, many minerals can appear in multiple colors. Therefore, observable specimen color is the least effective property in identification.
Streak--The color of a mineral in powdered form. A streak test is performed by dragging a freshly cleaved mineral surface across an unglazed porcelain surface. If the mineral is less hard than the porcelain, it will leave a stripe of color (the mineral in a powdered state). This is the true color of a mineral specimen as it lessens the impurity impact and eliminates the light distortion from the crystal. Although a mineral may have multiple observable specimen colors, it will only have one streak color.
Luster--Refers to the absorption, reflection, or refraction of light by the surface of a mineral. Minerals possess various lusters that are somewhat self-explanatory such as dull, earthy, adamantine, metallic, glassy, metallic, silky, greasy, pearly, and resinous.
Fluorescence--Some minerals fluoresce in ultraviolet light, and some minerals specimens may appear to fluoresce due to fluorescent mineral impurities, or due to locality. This is not an extremely reliable indicator property but can be used in conjunction with other identification properties.
Chemical Composition--Minerals are chemicals, either elements or compounds found naturally in the Earth. Some minerals have a fixed chemical composition, and some minerals have a rigid set of chemical composition parameters that allow for the replacement of certain elements with other elements. Chemical properties can be tested with the use of a blowpipe, flame color, bead test, and laboratory solution tests.
Hardness--Minerals are identified roughly by their hardness based on the Mohs scale of mineral hardness, a list of ten minerals from #1 (softest) to #10 (hardest). All minerals will fall somewhere along the scale, based on their ability to scratch any mineral with a number lower than theirs and their inability to scratch any mineral with a number higher than theirs.
