Mohs hårdhet
The scale was introduced in by the German geologist and mineralogist Friedrich Mohsin his book 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 ; [ 1 ] [ 2 ] [ a ] it mohs hårdhet one of several definitions of hardness in materials sciencesome of which are more quantitative.
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 Stonesc. AD The Mohs scale of mineral hardness is based on the ability of one natural sample of mineral to visibly scratch another mineral. Minerals are chemically pure solids found in nature. Rocks are mixtures of one or more minerals.
Diamond was the hardest known naturally occurring mineral when the scale was designed, and defines the top of the scale, arbitrarily set at 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 fluoriteits hardness on the Mohs scale would be between 4 and 5.
Technically, "scratching" a mohs hårdhet for the purposes of the Mohs scale means creating non- 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.
Each of the ten hardness values in the Mohs scale is represented by a reference mineralmost of which are widespread in rocks.
How the Mohs Scale Ranks Hardness
The Mohs scale is an ordinal scale. For example, corundum 9 is twice as hard as topaz 8but diamond 10 is four times as hard as corundum. Below is a table of more materials mohs hårdhet Mohs scale. Some of them have a hardness between two of the Mohs scale reference minerals. Some solid substances that are not minerals have been assigned a hardness on the Mohs scale.
However, hardness can make it difficult to determine if the substance is a mixture of other substances or if it may be misleading or meaningless. For example, some sources have assigned a Mohs hardness of 6 or 7 to granite but it is a rock made of several minerals, each with its own Mohs hardness e. Despite its lack of precision, the Mohs scale is relevant for field geologists, who mohs hårdhet it to roughly identify minerals using scratch kits.
Mohs scale - Wikipedia
The Mohs scale hardness mohs hårdhet minerals can be commonly found in reference sheets. Mohs hardness is useful in milling. It allows the assessment of which type of mill and grinding medium will best reduce a given product whose hardness is known. Electronic manufacturers use the scale for testing the resilience of flat panel display components such as cover glass for LCDs or encapsulation for OLEDsas well as to evaluate the hardness of touch screens in consumer electronics.
Comparison between Mohs hardness and Vickers hardness : [ 17 ]. Contents move to sidebar hide. Article Talk. Read Edit View history. Tools Tools.
Mohs Hardness Scale
Download as PDF Printable version. In other projects. Wikimedia Commons. Qualitative scale characterizing scratch resistance. Reference minerals [ edit ]. Examples [ edit ]. This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources in this section.
Mohs Hardness Scale - U.S. National Park Service
Unsourced material may be challenged and removed. Use [ edit ]. Comparison with Vickers scale [ edit ].
Footnotes [ edit ]. See also [ edit ]. References [ edit ]. Entwicklungsgeschichte der Mineralogischen Wissenschaften [ History of the development of the mineralogical sciences ] in German.