Mohs Scale
Uploaded by
ScribdTranslationsMohs Scale
Uploaded by
ScribdTranslationsMohs scale
Origin: Wikipedia, the free encyclopedia.
The Mohs scale quantifies ahardnesstwomineralsthat is, the resistance that a certain
mineral offers a scratch, that is, the removal of particles from its surface. The diamond scratches the
glass, therefore, this is harder than glass. This scale was created
in1812hairmineralogistGermanFriedrich Mohswith 10 minerals of different hardnesses
existing in the Earth's crust. Assigned values from 1 to 10. The hardness value of 1 was given to the material
less hard than it istalcumand the value 10 given to thediamondwhat is the hardest substance existing in
nature. This scale does not correspond to the absolute hardness of a material, for example, diamond.
has an absolute hardness 1500 times greater than talc. Between 1 and 9, the hardness increases more or
less uniform, but from 9 to 10 there is a very pronounced difference, because the diamond is very
harder than corundum (that is, than ruby and sapphire).
Durability
Mineral Chemical formula
a
1 Talc(can be easily scratched with a nail) Mg3Yes4O10(OH)2
Gypsum(orGessocan be scratched with a fingernail with a little more
2 CaSO4·2H2O
difficulty
3 Calcite, (can be scratched with a coin ofcopper) Calcium carbonate3
4 Fluorite(can be scratched with a kitchen knife) CaF2
5 Apatite(can be scratched difficultly with a kitchen knife) Ca5(PO4)3(OH-,Cl-,F-)
6 Feldspar/ Orthoclase(can be scratched with a metal alloy ofsteel) KAlSi3O8
7 Quartz, (capable of scratching the glass. Ex.:Amethyst) SiO2
8 Topaz(Capable of scratching quartz) Al2SiO4(OH-,F-)2
9 CorundumCapable of scratching the Topaz. Examples:SapphireeRuby) Al2O3
10Diamondthe hardest mineral that exists, can scratch any other and is C
scratched only by another diamond )
The Mohs hardness scale is used inmineralogy, however, there are other hardness scales.
used in materials science.
. Brinell hardness
. Rockwell hardness
. Superficial Rockwell hardness
. Webster's hardness
. Vickers hardness
http://en.wikipedia.org/wiki/Mohs_scale
Mohs Hardness Test
The Mohs scale was first used in 1822. It simply consists of a
group of 10 minerals, ranked from 1 to 10. Diamond is classified as the most
hard and has a rating of 10; the softest is talc, classified with a rating of 1. Each
A mineral on the scale can scratch all those below its index.
The intervals of the scale are not of the same value, that is, the interval between 9 and 10 is
much greater than between 1 and 2. The hardness is determined by the research of which
mineral of the standard scale the test material scratches or does not scratch. The hardness of the material
the test is between the two points of the scale, the first being the mineral scratched by
testing material and the second the mineral not scratched by the testing material.
Some examples of the hardness of common metals on the Mohs scale are: copper, between 2 and
3 and the tool steels, between 7 and 8.
This is a simple test, but it is not quantitative. The patterns are simply
arbitrary numbers.
Materials and metallurgy professionals typically do not use the Mohs scale.
It is just a qualitative indication when there are no devices available for the
conventional hardness tests.