Editing Mineral (section)

===Hardness===
{{main article|Mohs scale of mineral hardness}}
[[File:Rough diamond.jpg|right|thumb|Diamond is the hardest natural material, and has a Mohs hardness of 10.]]
The hardness of a mineral defines how much it can resist scratching or indentation. This physical property is controlled by the chemical composition and crystalline structure of a mineral. 

The most commonly used scale of measurement is the [[Ordinal data|ordinal]] Mohs hardness scale, which measures resistance to scratching. Defined by ten indicators, a mineral with a higher index scratches those below it. The scale ranges from talc, a [[phyllosilicate]], to diamond, a carbon polymorph that is the hardest natural material. The scale is provided below:<ref name="DG2829"/><ref name=2112.d/>

{| class="wikitable sortable"
|-
!Mohs hardness
!Mineral
!Chemical formulae
|-
|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,Cl,F)
|-
|6
|[[Orthoclase]]
|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,F)<sub>2</sub>
|-
|9
|[[Corundum]]
|Al<sub>2</sub>O<sub>3</sub>
|-
|10
|[[Diamond]]
|C
|}
[[File:Mohs-Hardness-Graph.svg|Mohs Scale versus Absolute Hardness|right|frameless]]
A mineral's hardness is a function of its structure. Hardness is not necessarily constant for all crystallographic directions; crystallographic weakness renders some directions softer than others.<ref name="DG2829">{{harvnb|Dyar|Gunter|2008}}, pp. 28–29</ref> An example of this hardness variability exists in kyanite, which has a Mohs hardness of 5{{frac|1|2}} parallel to [[Miller index|[001]]] but 7 parallel to [[Miller index|[100]]].<ref name="Kyanite">{{cite web|url=https://www.mindat.org/min-2303.html|title=Kyanite|access-date=3 April 2018|publisher=[[Mindat.org]]|archive-date=14 September 2019|archive-url=https://web.archive.org/web/20190914132555/https://www.mindat.org/min-2303.html|url-status=live}}</ref>

Other scales include these;<ref>{{cite web |title=Hardness: Vickers, Rockwell, Brinell, Mohs, Shore and Knoop - Matmatch |url=https://matmatch.com/learn/process/hardness-comparison |website=matmatch.com |access-date=4 October 2021 |archive-date=4 October 2021 |archive-url=https://web.archive.org/web/20211004171353/https://matmatch.com/learn/process/hardness-comparison |url-status=live }}</ref>
*[[Shore durometer|Shore's hardness test]], which measures the endurance of a mineral based on the indentation of a spring-loaded contraption.<ref>{{cite web |title=Hardness |url=http://www.calce.umd.edu/general/Facilities/Hardness_ad_.htm#3.5 |access-date=4 October 2021 |date=7 July 2007|archive-url=https://web.archive.org/web/20070707141201/http://www.calce.umd.edu/general/Facilities/Hardness_ad_.htm#3.5 |archive-date=2007-07-07 }}</ref>
*The [[Rockwell scale]]
*The [[Vickers hardness test]]
*The [[Brinell scale]]