 Each mineral has a definite chemical composition and crystalline structure.  These two characteristics are the fingerprint of the mineral  Various chemical tests in laboratories can be done on a mineral to determine its composition.  X-ray diffraction can be used to determine its crystalline structure.

 The procedures in the laboratories are time consuming and costly.  Of the 4000 minerals, only 20 are common, so identification becomes easier, as they can be determined for the most part by their physical characteristics.  The process still take practice and good observation skills

 Colour  Streak  Crystal habit  Hardness  Cleavage  Fracture  Lustre  Specific gravity

 The most obvious, but least reliable.  Many minerals can be found in different colours.  Example is Quartz – white, clear, purple, brown, pink, and black

 This test is very reliable.  Streak is the colour of the mineral in powder form.  The colour is found by scratching the mineral against a piece of porcelain (called a streak plate).

 The shape that we see of the mineral maybe a clue.  Some common crystal habits are:

 A crystal is an external expression of a mineral’s internal arrangement of atoms. All minerals have an orderly internal arrangement of atoms, but crystals are rarely observed in nature.  Minerals do not always form there natural characteristic because they are competing for space when they are growing. Therefore they need room to grow.  This means the mineral must either have the strength to grow in a space, or have an environment that allows for growth.

 This is the minerals resistance to scratching.  The degree of hardness is indicated with a number on the Moh’s Hardness Scale

 Cleavage is the tendency of some minerals, when struck to break along distinct planes.  These planes represent areas of weak bonding in the mineral’s crystal structure.  A mineral may cleave;  In one plane  Two planes at 90º  Two planes at angles other than 90º  Three planes at 90º  Three planes at angles other than 90º  Or a mineral may not cleave, which is called fracture

 The lustre of a mineral is the way its surface reflects light.  Most terms used to describe lustre are self-explanatory: metallic, earthy, waxy, greasy, vitreous (glassy), adamantine (or brilliant, as in a faceted diamond).  It will be necessary, at least at first, only to distinguish between minerals with a metallic lustre and those with one of the non-metallic lustres.  A metallic lustre is a shiny, opaque appearance similar to a bright chrome bumper on an automobile.  Other shiny, but somewhat translucent or transparent lustres (glassy, adamantine), along with dull, earthy, waxy, and resinous lustres, are grouped as non- metallic.

 The specific gravity of a substance is a comparison of its density to that of water.  Specific gravity can be measured precisely, or estimated by a comparison.  To compare the specific gravity of any two minerals, simply hold a sample of one in your hand and "heft it," i.e., get a feeling for its weight.  Then heft a sample of the other that is approximately the same size.  If there is a great difference in specific gravity, you will detect it easily. It is often sufficient to note whether a mineral's specific gravity is significantly higher or lower than that of other minerals.

 These physical characteristics should be used in combination to identify a mineral.  A Mineral Identification Key is a good tool to use when start out with the identification of minerals