The Mohs Scale Of Mineral Hardness

The Mohs scale of mineral hardness is a scale of hardness used in classifying minerals.

 

The Mohs Scale and Diamonds

 

Mohs was looking for a way to determine the hardness of minerals. The principle to determine hardness was made by observing which minerals can scratch others. The Mohs hardness scale includes all ten known minerals in nature.

Mohs determined that diamond is the hardest mineral in nature, assigning him with the highest number on the scale – 10. Following in hardness are: Corundum, Sapphire (9), Topaz (8), Quartz (7), Feldspar (6), Apatite (5), Fluorite (4), Calcite (3), Gypsum (2), Talc (1).

The Mohs scale is unique in that there is an uneven range of hardness between the minerals. The hardness of a diamond (10) compared to Corundums and Sapphires (9) is much larger than the hardness between Corundums and Sapphires and the next hardest mineral – Topaz (8).

Friedrich Mohs

 

Friedrich Mohs (1773-1832) was a German scientist, geologist and mineralogist. Born in the town of Gernrode, Germany. Mohs showed an interest in science from an early age. He studied chemistry, mathematics and physics at the University of Halle and later studied at the Mining Academy in Freiberg in Saxony. As a mineralogist, he attempted to identify and classify minerals according to their physical characteristics rather than their chemical composition – the common classification method of the day.

He based his work on the classifications of both Theophrastus and Pliny the Elder, who compared the relative hardness of minerals, including diamond and quartz, by scratching minerals with one another. In 1812, Mohs created the Mohs scale of mineral hardness, which is used to this day.

Mohs scale