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