Mohs Hardness Scale
The ability of a solid substance to resist surface deformation or
abrasion. In mineralogy, hardness is defined as the resistance of the smooth
surface of a mineral to scratching. It is determined by the Mohs scale of
hardness, named for German mineralogist Friedrich Mohs. In the Mohs scale,
ten common minerals are arranged in order of increasing hardness and
assigned numbers:
- talc
- gypsum Baking Soda (2.5)
- calcite, Kieserite (magnesium
sulfate) (3.5)
- fluorite, Corn cob (4.5)
- apatite
- orthoclase ( feldspar)
- quartz
CRYSTAL GRIT
Garnet
- topaz
- corundum
- diamond
The hardness of a given mineral specimen is then determined by which
mineral in the Mohs scale will scratch it.
In metallurgy and engineering, hardness is determined by impressing a
hard material on the surface to be tested and measuring the size of the
indentation. This is known as the Brinell test, after Swedish engineer
Johann Brinell.
|
