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Encyclopedia > Mohs scale of mineral hardness

The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created in 1812 by the German mineralogist Friedrich Mohs and is one of several definitions of hardness in materials science. The method however, is of great antiquity, and is first mentioned by Pliny the Elder in his Naturalis Historia first published in about 77 AD. For other uses, see Mineral (disambiguation). ... Mineralogy is an earth science that involves the chemistry, crystal structure, and physical (including optical) properties of minerals. ... Friedrich Mohs (January 29, 1773 - September 29, 1839) was a German geologist/mineralogist. ... In materials science, hardness is the characteristic of a solid material expressing its resistance to permanent deformation. ... The Materials Science Tetrahedron, which often also includes Characterization at the center Materials science or Materials Engineering is an interdisciplinary field involving the properties of matter and its applications to various areas of science and engineering. ... Pliny the Elder: an imaginative 19th Century portrait. ... Naturalis Historia Pliny the Elders Natural History is an encyclopedia written by Pliny the Elder. ...

Contents

Minerals

Mohs based the scale on ten minerals that are all readily available. As the hardest known naturally occurring substance, diamond is at the top of the scale. The hardness of a material is measured against the scale by finding the hardest material that the given material can scratch, and/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 fall between 4 and 5.


The Mohs scale is a purely ordinal scale. For example, corundum (9) is twice as hard as topaz (8), but diamond (10) is almost four times as hard as corundum. The table below shows comparison with absolute hardness measured by a sclerometer, with pictorial examples. The level of measurement of a variable in mathematics and statistics is a classification that was proposed in order to describe the nature of information contained within numbers assigned to objects and, therefore, within the variable. ... Corundum (from Tamil kurundam) is a crystalline form of aluminium oxide and one of the rock-forming minerals. ... This article is about the mineral or gemstone. ... The sclerometer (from the Ancient Greek skleros meaning hard) is a mineralogists (usually) instrument used to measure the hardness of materials. ...

Hardness Mineral Absolute Hardness Image
1 Talc (Mg3Si4O10(OH)2) 1
2 Gypsum (CaSO4·2H2O) 2
3 Calcite (CaCO3) 9
4 Fluorite (CaF2) 21
5 Apatite (Ca5(PO4)3(OH-,Cl-,F-) 48
6 Orthoclase (KAlSi3O8) 72
7 Quartz (SiO2) 100
8 Topaz (Al2SiO4(OH-,F-)2) 200
9 Corundum (Al2O3) 400
10 Diamond (C) 1500


On the Mohs scale, a pencil lead has a hardness of 1; a fingernail has hardness 2.5; a copper penny, about 3.5; a knife blade, 5.5; window glass, 5.5; steel file, 6.5.[1] Using these ordinary materials of known hardness can be a simple way to approximate the position of a mineral on the scale. Talc (derived from the Persian via Arabic talq) is a mineral composed of hydrated magnesium silicate with the chemical formula H2Mg3(SiO3)4 or Mg3Si4O10(OH)2. ... Image File history File links Talc_block. ... For other uses, see Gypsum (disambiguation). ... Photograph of gypsum specimen from New South Wales, Australia taken by Dlloyd. ... Doubly refracting Calcite from Iceberg claim, Dixon, New Mexico. ... Fluorite (also called fluorspar) is a mineral composed of calcium fluoride, CaF2. ... Image File history File links Metadata Size of this preview: 682 × 600 pixelsFull resolution (2374 × 2088 pixel, file size: 2. ... Apatite is a group of phosphate minerals, usually referring to hydroxylapatite, fluorapatite, and chlorapatite, named for high concentrations of OH-, F-, or Cl- ions, respectively, in the crystal. ... Image File history File links Download high resolution version (2240x1348, 2135 KB) Summary Two crystals, 1. ... Orthoclase (KAlSi3O8) is an important tectosilicate mineral, which forms igneous rock. ... Image File history File links Mineraly. ... -1... Image File history File links No higher resolution available. ... This article is about the mineral or gemstone. ... Corundum (from Tamil kurundam) is a crystalline form of aluminium oxide and one of the rock-forming minerals. ... ImageMetadata File history File links Cut_Ruby. ... This article is about the mineral. ... Wikipedia does not have an article with this exact name. ... This article discusses the anatomical nail. ... Detail of a double-cut flat file A file (or hand-file) is a hand tool used to shape material by cutting. ...


Intermediate hardness

The table below incorporates additional substances that may fall between levels::

Hardness Substance or Mineral
1 Talc
2 Gypsum
2.5 to 3 pure gold, silver, aluminium
3 Calcite, copper penny
4 Fluorite
4 to 4.5 Platinum
4 to 5 Iron
5 Apatite
6 Orthoclase
6 Titanium
6.5 Iron pyrite
6 to 7 Glass, Vitreous pure silica
7 Quartz
7 to 7.5 Garnet
7 to 8 Hardened steel
8 Topaz
9 Corundum
9 to 9.5 Carborundum
<10 Ultrahard fullerite
10 Diamond
>10 Aggregated diamond nanorods

Talc (derived from the Persian via Arabic talq) is a mineral composed of hydrated magnesium silicate with the chemical formula H2Mg3(SiO3)4 or Mg3Si4O10(OH)2. ... For other uses, see Gypsum (disambiguation). ... GOLD refers to one of the following: GOLD (IEEE) is an IEEE program designed to garner more student members at the university level (Graduates of the Last Decade). ... This article is about the chemical element. ... Aluminum redirects here. ... Doubly refracting Calcite from Iceberg claim, Dixon, New Mexico. ... For other uses, see Copper (disambiguation). ... This article is about the coin. ... Fluorite (also called fluorspar) is a mineral composed of calcium fluoride, CaF2. ... General Name, Symbol, Number platinum, Pt, 78 Chemical series transition metals Group, Period, Block 10, 6, d Appearance grayish white Standard atomic weight 195. ... Fe redirects here. ... Apatite is a group of phosphate minerals, usually referring to hydroxylapatite, fluorapatite, and chlorapatite, named for high concentrations of OH-, F-, or Cl- ions, respectively, in the crystal. ... Orthoclase (KAlSi3O8) is an important tectosilicate mineral, which forms igneous rock. ... General Name, symbol, number titanium, Ti, 22 Chemical series transition metals Group, period, block 4, 4, d Appearance silvery grey-white metallic Standard atomic weight 47. ... The mineral pyrite, or iron pyrite, is iron disulfide, FeS2. ... This article is about the material. ... A sphere manufactured by NASA out of fused quartz for use in a gyroscope in the Gravity Probe B experiment. ... -1... For other uses, see Garnet (disambiguation). ... The term hardened steel is often used for a medium or high carbon steel that has been given the heat treatments of quenching followed by tempering. ... This article is about the mineral or gemstone. ... Corundum (from Tamil kurundam) is a crystalline form of aluminium oxide and one of the rock-forming minerals. ... Silicon carbide (SiC) or moissanite is a ceramic compound of silicon and carbon. ... The C60 fullerene in crystalline form Fullerites are the solid-state manifestation of fullerenes and related compounds and materials. ... This article is about the mineral. ... Aggregated diamond nanorods, or ADNRs, are an allotrope of carbon believed to be the hardest and least compressible known material, as measured by its isothermal bulk modulus; aggregated diamond nanorods have a modulus of 491 gigapascals (GPa), while a conventional diamond has a modulus of 442 GPa. ...

Also see

Look up hardness in Wiktionary, the free dictionary. ... The Vickers hardness test was developed in the early 1920s and uses a pyramid-shaped indenter made of diamond. ...

References

Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 231st day of the year (232nd in leap years) in the Gregorian calendar. ... is the 111th day of the year (112th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 231st day of the year (232nd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... In mineralogy, shape and size give rise to descriptive terms applied to the typical appearance, or habit of crystals. ... A crystal system is a category of space groups, which characterize symmetry of structures in three dimensions with translational symmetry in three directions, having a discrete class of point groups. ... Lustre (American English: luster) is a description of the way light interacts with the surface of a crystal, rock or mineral. ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... The streak (also called powder color) of a mineral is the color of the powder produced when it is dragged across a unweathered surface. ...

  Results from FactBites:
 
Baxter’s The Jewellers, Birthstone Information (2514 words)
On the Mohs scale of hardness aquamarine measures 7-5 to 8 and is therefore a durable stone.
Sapphire and ruby have a hardness of 9 on the Mohs scale.
Mohs' scale of hardness was developed by Friedrich Mohs (1773-1839) and measures the hardness of "rock" on a scale of 1 to 10.
Desert Moissanite-Exquisite Moissanite! (672 words)
The Mohs Scale is used to determine the hardness of solids, especially minerals.
The hardness of a mineral is a measure of its ability to resist abrasion or scratching by other minerals or by an object of known hardness.
The scale consists of 10 minerals arranged in increasing hardness with 1 being the softest.
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