Minerals can be classified by their properties (optical, physical,  electrical,  magnetic) and  by their chemical composition. Minerals can, therefore, be identified by spectroscopic or visual observation; however, chemical analysis is the only means of identifying the precise nature of the mineral.

Hardness of the mineral

In 1822, a German mineralogist named Friedrich Mohs established a measuring scale to determine the hardness of each  mineral,  called the Mohs scale of mineral  hard- ness. This scale is widely used  today. Each mineral  can

be compared to 10 comparative minerals  ranging from soft to hard.  The comparative minerals  used  are: talc, plaster,  calcite, fluorite,  apatite, feldspar,  quartz, topaz, corundum and  diamond.

Tenacity or cohesion

A mineral’s tenacity or cohesion is the degree of resis- tance that  it offers to breakage, deformation, crushing, curvature, or pulverization. The following classes of tenacity are defined:

Fracture of a mineral

When a mineral  is fractured, it separates in a number of different  ways:

Exfoliation: Describes  a mineral  that  separates with flat and  parallel surfaces.

Examples: mica, galena, fluorita and plaster