| One of a minerals most useful diagnostic properties is hardness. The usefulness of
hardness is its consistency. Specimens of the same mineral may vary slightly from one to
another, but generally they are quite consistent. Inconsistencies occur when the specimen
is impure, poorly crystallized, or actually an aggregate and not an individual crystal. |
| Hardness can be tested through scratching a mineral of an unknown hardness against one
of a known hardness. A mineral can only be scratched by a harder substance. A hard mineral
can scratch a softer mineral, but a soft mineral can not scratch a harder mineral (no
matter how hard you try). Therefore, a relative scale can be
established to account for the differences in hardness simply by determining which mineral
scratches another. |
| Mohs scale of mineral hardness was proposed by Frederich Mohs (1773-1839), who selected
the 10 minerals because they were common or readily available. The scale is not a linear
scale, but relative. Mohs Hardness Scale starts with talc as 1 and ends with diamond
as 10 and measures how well a mineral resists being scratched. |
