View source for Mohs scale of mineral hardness

The '''Mohs scale of mineral hardness''' (or simply '''Mohs scale''') is a qualitative ordinal scale characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material.

==General==
The Mohs scale of mineral hardness is based on the ability of one natural sample of mineral to scratch another mineral visibly. The samples of matter used by Mohs are all different minerals. Minerals are pure substances found in nature.

The Mohs scale is a purely ordinal scale. For example, corundum (9) is twice as hard as topaz (8), but diamond (10) is four times as hard as corundum.

==Minerals==
===Classical scale===
{| class="wikitable sortable" style="text-align:center"
|-
!Mohs hardness
!Mineral
!Chemical formula
!class="unsortable"|Image
|-
|'''1'''
|Talc
|Mg<sub>3</sub>Si<sub>4</sub>O<sub>10</sub>(OH)<sub>2</sub>
|
|-
|'''2'''
|Gypsum
|CaSO<sub>4</sub>·2H<sub>2</sub>O
|
|-
|'''3'''
|Calcite
|CaCO<sub>3</sub>
|
|-
|'''4'''
|Fluorite
|CaF<sub>2</sub>
|
|-
|'''5'''
|Apatite
|Ca<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(OH<sup>−</sup>,Cl<sup>−</sup>,F<sup>−</sup>)
|
|-
|'''6'''
|Orthoclase feldspar
|KAlSi<sub>3</sub>O<sub>8</sub>
|
|-
|'''7'''
|Quartz
|SiO<sub>2</sub>
|
|-
|'''8'''
|Topaz
|Al<sub>2</sub>SiO<sub>4</sub>(OH<sup>−</sup>,F<sup>−</sup>)<sub>2</sub>
|
|-
|'''9'''
|Corundum
|Al<sub>2</sub>O<sub>3</sub>
|
|-
|'''10'''
|Diamond
|C
|
|}

===Intermediate scale===
{| class="wikitable"
|-
!Hardness
!Substance or mineral
|-
| style="text-align:center;"|0.2–0.3
|[[caesium]], [[rubidium]]
|-
| style="text-align:center;"|0.5–0.6
|[[lithium]], [[sodium]], [[potassium]]
|-
| style="text-align:center;"|1
|talc
|-
| style="text-align:center;"|1.5
|[[gallium]], [[strontium]], [[indium]], [[tin]], [[barium]], [[thallium]], [[lead]], [[carbon|graphite]], [[water|ice]]<ref>[http://www.messenger-education.org/library/pdf/ice_mineral.pdf "Ice is a mineral"] in ''Exploring Ice in the Solar System''. messenger-education.org</ref>
|-
| style="text-align:center;"|2
|hexagonal [[boron nitride]],<ref> Berger, Lev I. (1996). Semiconductor Materials (First ed.). Boca Raton, FL: CRC Press. p. 126</ref> [[calcium]], [[selenium]], [[cadmium]], [[sulfur]], [[tellurium]], [[bismuth]], [[calcium sulfate|gypsum]]
|-
| style="text-align:center;"|2–2.5
|[[sodium chloride|halite]] (rock salt)
|-
| style="text-align:center;"|2.5–3
| [[gold]], [[silver]], [[aluminium]], [[zinc]], [[lanthanum]], [[cerium]], Jet (lignite)
|-
| style="text-align:center;"|3
| [[calcium carbonate|calcite]], [[copper]], [[arsenic]], [[antimony]], [[thorium]], dentin
|-
| style="text-align:center;"|3.5
| [[platinum]]
|-
| style="text-align:center;"|4
| [[calcium fluoride|fluorite]], [[iron]], [[nickel]]
|-
| style="text-align:center;"|4–4.5
|[[steel]]
|-
| style="text-align:center;"|5
| apatite (tooth enamel), [[zirconium]], [[palladium]], obsidian (volcanic glass)
|-
| style="text-align:center;"|5.5
| [[beryllium]], [[molybdenum]], [[hafnium]], [[glass]], [[cobalt]]
|-
| style="text-align:center;"|6
| orthoclase, [[titanium]], [[manganese]], [[germanium]], [[niobium]], [[rhodium]], [[uranium]]
|-
| style="text-align:center;"|6–7
| [[silicon dioxide|fused quartz]], iron pyrite, [[silicon]], [[ruthenium]], [[iridium]], [[tantalum]], opal, peridot, tanzanite, jade
|-
| style="text-align:center;"|7
| [[osmium]], [[silicon dioxide|quartz]], [[rhenium]], [[vanadium]]
|-
| style="text-align:center;"|7.5–8
| emerald, hardened [[steel]], [[tungsten]], spinel
|-
| style="text-align:center;"|8
| topaz, cubic zirconia
|-
| style="text-align:center;"|8.5
| chrysoberyl, [[chromium]], [[silicon nitride]], [[tantalum carbide]]
|-
| style="text-align:center;"| 9
| [[aluminium oxide|corundum]], [[tungsten carbide]], [[titanium nitride]]
|-
| style="text-align:center;"| 9–9.5
| [[silicon carbide|silicon carbide (carborundum)]], [[titanium carbide]]
|-
| style="text-align:center;"|9.5–10
| [[boron]], [[boron carbide]], [[boron nitride]], rhenium diboride (''a''-axis),<ref name=AFM>{{cite web | url = http://tolbert.chem.ucla.edu/Publication/AdvFuncMater-19-p3519.pdf | pages = 3526–3527 | title=
Advancements in the Search for Superhard Ultra-Incompressible Metal Borides | author1= Levine, Jonathan B. | author2= Tolbert, Sarah H. | author3= Kaner, Richard B. | doi= 10.1002/adfm.200901257 | journal = Advanced Functional Materials | year =2009}}</ref> stishovite, titanium diboride
|-
| style="text-align:center;"|10
| [[carbon|diamond]], carbonado
|-
| style="text-align:center;"|>11
| nanocrystalline diamond (hyperdiamond, ultrahard fullerite), rhenium diboride (''c''-axis)<ref name =AFM/>
|}

==References==
<references/>
===Relevant Sciencemadness threads===
*[http://www.sciencemadness.org/talk/viewthread.php?tid=144728 What is theory behind mohs hardness, files, sandpapers?]

[[Category:Concepts]]
[[Category:Data tables]]