Editing Mohs scale (section)

==Reference minerals==
The Mohs scale of mineral hardness is based on the ability of one natural sample of mineral to visibly scratch another mineral. [[Mineral]]s are chemically pure solids found in nature. [[Rock (geology)|Rock]]s are mixtures of one or more minerals. 
:{| style="float:right;border:none;background:white;margin-left:2em"
|- style="text-align:center;"
| [[File:Mohs scale vs absolute hardness.png|frameless|center|300px]]
|-
|style="padding-left:2em;"| Mohs scale along the horizontal axis matched with <br/>one of the [[absolute hardness]] scales along the <br/>vertical. Vertical scale is logarithmic. 
|}
[[Diamond]] was the hardest known naturally occurring mineral when the scale was designed, and defines the top of the scale, arbitrarily set at 10. The hardness of a material is measured against the scale by finding the hardest material that the given material can scratch, or the softest material that can scratch the given material. For example, if some material is scratched by [[apatite]] but not by [[fluorite]], its hardness on the Mohs scale would be between 4 and 5.<ref>{{cite web |title=Mohs scale of mineral hardness |publisher=[[American Federation of Mineralogical Societies]] |url=https://www.amfed.org/mohs-scale |via=amfed.org |access-date= }}</ref>

Technically, "scratching" a material for the purposes of the Mohs scale means creating non-[[Elasticity (physics)|elastic]] dislocations visible to the naked eye. Frequently, materials that are lower on the Mohs scale can create microscopic, non-elastic dislocations on materials that have a higher Mohs number. While these microscopic dislocations are permanent and sometimes detrimental to the harder material's structural integrity, they are not considered "scratches" for the determination of a Mohs scale number.<ref>{{cite report |last=Geels |first=Kay |publication-date=26 April 2000 |section=The true microstructure of materials |pages=5–13 |title=Materialographic Preparation from Sorby to the Present |department=Application notes and guides |series=The Struers metallographic library |publisher=Struers A/S |place=Copenhagen, DK |url=http://www.struers.com/resources/elements/12/2474/35art2.pdf |url-status=dead <!-- presumed --> |archive-url=https://web.archive.org/web/20160307194802/http://www.struers.com/resources/elements/12/2474/35art2.pdf |archive-date=7 March 2016 }}</ref>

Each of the ten hardness values in the Mohs scale is represented by a ''reference mineral'', most of which are widespread in rocks.

The Mohs scale is an [[ordinal scale]]. For example, [[corundum]] (9) is twice as hard as [[topaz]] (8), but diamond (10) is four times as hard as corundum.{{fact|date=October 2024}} The table below shows the comparison with the [[absolute hardness]] measured by a [[sclerometer]], with images of the reference minerals in the rightmost column.<ref>{{cite web |title=What is important about hardness? |department=Amethyst galleries |series=Mineral gallery |url=http://www.galleries.com/minerals/hardness.htm |url-status=dead <!-- presumed --> |access-date= |via=galleries.com |archive-url=https://web.archive.org/web/20061230174242/http://www.galleries.com/minerals/hardness.htm |archive-date=30 December 2006 }}</ref><ref>{{cite web |title=Mineral hardness and hardness scales |publisher=Inland Lapidary |url=http://www.inlandlapidary.com/user_area/hardness.asp |via=inlandlapidary.com |url-status=live <!-- presumed --> |access-date= |archive-url=https://web.archive.org/web/20081017152845/http://www.inlandlapidary.com/user_area/hardness.asp |archive-date=2008-10-17 }}</ref>

:{| class="wikitable sortable" style="text-align:center"
|-
! Mohs<br/>hardness
! Reference<br/>mineral
! Chemical&nbsp;formula
! Absolute<br/>hardness<ref>{{cite book |last=Mukherjee |first=Swapna |year=2012 |title=Applied Mineralogy: Applications in industry and environment |publisher=Springer Science & Business Media |isbn=978-94-007-1162-4 |page=373 |url=https://books.google.com/books?id=mllvP7ZmWqkC&pg=PA373 |via=Google books}}</ref>
!class="unsortable"| Example image
|-
| '''1'''
| [[Talc]]
| {{chem2| Mg3Si4O10(OH)2 }} <!-- Mg<sub>3</sub>Si<sub>4</sub>O<sub>10</sub>(OH)<sub>2</sub> -->
| 1
| [[Image:Talc block.jpg|100px]]
|-
| '''2'''
| [[Gypsum]]
| {{chem2| CaSO4*2H2O }} <!-- CaSO<sub>4</sub>·2H<sub>2</sub>O -->
| 2
| [[Image:Gypse Arignac.jpg|100px]]
|-
| '''3'''
| [[Calcite]]
| {{chem2| CaCO3 }} <!-- CaCO<sub>3</sub> -->
| 14
| [[Image:Calcite-sample2.jpg|100px]]
|-
| '''4'''
| [[Fluorite]]
| {{chem2| CaF2 }} <!-- CaF<sub>2</sub> -->
| 21
| [[Image:Fluorite with Iron Pyrite.jpg|100px]]
|-
| '''5'''
| [[Apatite]]
| {{chem2| Ca5(PO4)3(OH,Cl,F) }} <!-- Ca<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(OH<sup>−</sup>,Cl<sup>−</sup>,F<sup>−</sup>) -->
| 48
| [[Image:Apatite Canada.jpg|100px]]
|-
| '''6'''
| [[Orthoclase|Orthoclase<br/>feldspar]]
| {{chem2| KAlSi3O8 }} <!-- KAlSi<sub>3</sub>O<sub>8</sub> -->
| 72
| [[Image:OrthoclaseBresil.jpg|100px]]
|-
| '''7'''
| [[Quartz]]
| {{chem2| SiO2 }} <!-- SiO<sub>2</sub> -->
| 100
| [[Image:Quartz Brésil.jpg|100px]]
|-
| '''8'''
| [[Topaz]]
| {{chem2| Al2SiO4(OH,F)2 }} <!-- Al<sub>2</sub>SiO<sub>4</sub>(OH<sup>−</sup>,F<sup>−</sup>)<sub>2</sub> -->
| 200
| [[Image:Topaz-120187.jpg|100px]]
|-
| '''9'''
| [[Corundum]]
| {{chem2| Al2O3 }} <!-- Al<sub>2</sub>O<sub>3</sub> -->
| 400
| [[Image:Corundum-dtn14b.jpg|100px]]
|-
| '''10'''
| [[Diamond]]
| {{chem2| C }} <!-- C -->
| 1500
| [[Image:Rough diamond.jpg|100px]]
|}