A mineral maybe defined as a naturally occurring inorganic homogeneous solid with a characteristics chemical composition, and usually possessing atomic structures, which can be express into crystalline formation or other physical properties visible under polarizing petrographic microscopes. The composition of a mineral is nearly constant so that assignation of chemical formula is specific. These minerals have ordered atomic arrangement with individual characteristics making them distinguishable from one another.

Minerals can be evaluated in several ways under polarizing petrographic microscope. Several properties of minerals may be determined by examining them by using ordinary transmitted light, which do not use any of the polarizer and analyzer accessories. These two instruments are swung out of the axis of the polarized microscope. This method of examination is usually applied for transparent minerals. Another way of evaluation is by using a reflected light. With the use of reflected light, two other ways of examination can be made. First is by inserting the upper nicol or the polarizer accessory. This will now be an examination of a mineral in polarized light microscope. The next evaluation will be the use of the lower nicol or the analyzer as an additional accessory to be inserted into the axis of the petrographic polarizing microscope. These two nicols are rotated to such a position, where even in an empty stage, no light reaches the eye.

A mineral have several physical and optical properties identified. Among these are Among these are crystal forms and habits, hardness, color, luster, relief, cleavage, streak, specific gravity, tenacity, fracture pleochroism, birefringence, index of refraction and many others. All these can be seen when the mineral is viewed with the aid of geological polarizing microscopes. Most commonly used in this field with clear images exhibited is the petrographic polarizing microscope. It is always recommended that minerals should be evaluated and examined with great care and in a precise manner so as not to be confused with several similar properties to be found in different mineral types.