Five properties to identify minerals?
There are many properties useful in identifying minerals. The five that are most useful are cleavage, crystal habit, hardness, luster, and streak.
Properties of Minerals The following physical properties of minerals can be easily used to identify a mineral: Color Streak Hardness Cleavage or Fracture Crystalline Structure Diaphaneity or Amount of Transparency Tenacity Magnetism Luster Odor Taste Specific Gravity Read more: http://wiki.answers.com/Q/What_are_some_physical_properties_of_minerals#ixzz1NqIejipG
Some minerals are easier to identify than others because many have unique properties that make them different. For example gold is a very heavy metal and is extremely "soft" unlike "fools gold" which is brittle and cant be shaped. They are both similar in appearance but extremely different in traits.
Each mineral has a specific chemical composition and is different from the other minerals by some physical properties. Chemical properties: chemical composition, solubility in water or acids, reaction with some reagents, etc. Physical properties: color, luster, radioactivity, density, Mohs hardness, refraction index (and other optical characteristics), transparency, fluorescence, X-ray diffraction data, etc.