Editing Mohs scale (section)

{{short description|Qualitative scale characterizing scratch resistance}}
{{use dmy dates|date=August 2024}}
[[File:Mohssche-haerteskala hg.jpg|thumb|alt=Open wooden box with ten compartments, each containing a numbered mineral specimen.|Mohs hardness kit, containing one specimen of each mineral on the ten-point hardness scale]]

The '''Mohs scale''' ({{IPAc-en|m|ou|z}} {{respell|MOHZ}}) of mineral hardness is a [[Qualitative property|qualitative]] [[ordinal scale]], from 1 to 10, characterizing [[scratch hardness|scratch resistance]] of [[mineral]]s through the ability of harder material to scratch softer material.

The scale was introduced in 1812 by the German [[geologist]] and [[Mineralogy|mineralogist]] [[Friedrich Mohs]], in his book {{lang|de|Versuch einer Elementar-Methode zur naturhistorischen Bestimmung und Erkennung der Fossilien}} (English: Attempt at an elementary method for the natural-historical determination and recognition of fossils);<ref name=VonGroth1926>{{cite book | title=Entwicklungsgeschichte der Mineralogischen Wissenschaften | trans-title=History of the development of the mineralogical sciences | url=https://books.google.com/books?id=tD0LAQAAIAAJ&q=+Härteskala+1812 | publisher=Springer | last=von Groth | first=Paul Heinrich | date=1926 | publication-place=Berlin | page=250 | isbn=9783662409107 | lang=de }}</ref><ref name=Brit>{{cite encyclopedia |url=https://www.britannica.com/EBchecked/topic/387714/Mohs-hardness |title=Mohs hardness |encyclopedia=[[Encyclopædia Britannica]] |edition=online }}</ref>{{efn|
: {{lang|de|In demselben Jahre (1812) wurde MOHS als Professor am Joanneum angestellt und veröffentliche den ersten Teil seines Werkes {{noitalic|Versuch einer Elementarmethode zur naturhistorischen Bestimmung und Erkennung der Fossilien}}, in welcher die bekannte Härteskala aufgestellt wurde.}} — {{harvp|von Groth|1926}}
: &nbsp;
: In the same year (1812) MOHS was employed as a professor at the Joanneum and published the first part of his work ''Attempt at an elementary method for the natural-historical determination and recognition of fossils'', in which the well-known hardness scale was set up.<ref name=VonGroth1926/>
}} it is one of several definitions of [[hardness comparison|hardness]] in [[materials science]], some of which are more quantitative.<ref name="MinSocAm">{{cite web |title=Mohs scale of hardness |publisher=[[Mineralogical Society of America]] |url=http://www.minsocam.org/MSA/collectors_corner/article/mohs.htm |access-date=10 February 2021}}</ref>

The method of comparing hardness by observing which minerals can scratch others is of great antiquity, having been mentioned by [[Theophrastus]] in his treatise ''On Stones'', {{circa| 300 BC}}, followed by [[Pliny the Elder]] in his ''[[Natural History (Pliny)|Naturalis Historia]]'', {{circa| AD 77}}.<ref>{{cite book |url=http://www.farlang.com/gemstones/theophrastus-on-stones/page_148/view?searchterm=scratch |title=Theophrastus on Stones |author=[[Theophrastus]] |via=Farlang.com |access-date=2011-12-10}}</ref><ref>{{cite book |author=[[Pliny the Elder]] |title=Naturalis Historia |chapter=Book&nbsp;37, Chap.&nbsp;15 |chapter-url=https://www.perseus.tufts.edu/cgi-bin/ptext?lookup=Plin.+Nat.+37.15 |quote=''Adamas'': Six varieties of it. Two remedies.}}</ref><ref>{{cite book |author=[[Pliny the Elder]] |title=[[Naturalis Historia]] |chapter=Book&nbsp;37, Chap.&nbsp;76 |chapter-url=https://www.perseus.tufts.edu/cgi-bin/ptext?lookup=Plin.+Nat.+37.76 |quote=The methods of testing precious stones.}}</ref> The Mohs scale is useful for identification of minerals in the [[Field research|field]], but is not an accurate predictor of how well materials endure in an industrial setting.<ref>{{cite web |url=http://www.ndt-ed.org/EducationResources/CommunityCollege/Materials/Mechanical/Hardness.htm |title=Hardness |archive-url=https://web.archive.org/web/20140214185403/http://www.ndt-ed.org/EducationResources/CommunityCollege/Materials/Mechanical/Hardness.htm |archive-date=2014-02-14 |publisher=Non-Destructive Testing Resource Center |series=Materials Mechanical Hardness}}</ref>