Created by Friedrich Mohs in 1812, the Mohs scale has served as one the measures of hardness in materials sciences and the preeminent measure in gemology. With the diamond being the hardest mineral and talc crumbling if you just look at it, the test of a mineral is where it falls in the scratching order. A number of minerals fall in between numbers on the scale. An example are emeralds, which can be scratched by topaz, but are unaffected by quartz. They fall at 7.5 on the Mohs scale.
Hardness
Mineral
Associations and Uses
1
Talc
Talcum powder.
2
Gypsum
Plaster of paris, building materials. Formed when seawater evaporates from the earth’s surface.
3
Calcite
Limestone a great number of shells contain calcite.
4
Fluorite
Used in making apalescent glass and certain kinds of enamels
5
Apatite
One of the softest stones used in lapidary work, known to splinter and chip if cut improperly.
6
Orthoclase Feldspar
Used in cleansing powders and porcelain, the gemstone version is cut as moonstones.
7
Quartz
One of the world's most common minerals, amethyst, citrine and carnelian are a few of the popular forms of quartz. Ametrine is a natural amalgalm of amethyst and citrine.
8
Topaz
Typically transparent, the natural coloration of a golden topaz is due to impurities. Treated with heat, a topaz can be seen in an extraordinary range of colors.
9
Corundum
Sapphire and ruby are varieties of corundum. Emery stone is ground for polishing and finishing.
10
Diamond
Used in jewelry and cutting tools. Four times as hard as corundum. The source of much tsouris in the areas where mined.