In both material science and mineralogy, hardness refers to the property of a material which enables it to resist plastic deformation, induced either by penetration, indentation, or scratching. It is the measure of resistance to scratching or abrasion of one material to another or simply the ability of a material to resist damage.
Hardness is an important property of a material and it often determines what it can be used for. Certain substances prove harder than another when subjected to mechanical indentation or scratching. For example, materials made from ceramic can withstand high temperatures and resist non-elastic scratching than plastic materials.
Measuring hardness
There are many ways in which the hardness of a material can be measured. These tests are often empirical, based on experiments and observation rather than fundamental theory. Most of these testing process involves the material being subjected to either scratching or indentation.
In scratching, the most common method is the used of the Mohs scale and the instrument used in measuring the absolute hardness is called the sclerometer. The higher the absolute hardness, the greater it resistance to scratching and vice versa. The mohs scale of mineral hardness is a qualitative ordinal scale, based on the ability of one sample of mineral to scratch another mineral visibly. The higher a mineral is on the mohs scale, the more resistance it is to be scratched by another mineral. In other words, minerals having a higher number on the mohs scale can visible create a non-elastic deformation on minerals lower on the mohs scale.
Below is a brief review of the top ten strongest minerals on earth, based on the mohs scale.
Top ten hardest natural substances on earth.
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10. TALC
Talc is a type of clay mineral mined from the earth, composing of hydrated magnesium sulfate with the chemical formula .... Talc usually appears as greenish, whitish, greyish and even as a colorless rocky material. Talc is mostly used in cosmetic and personal care products, ranging from baby powders to eye shadows. The widely known talcum powder is gotten from a finely crushed talc. Talc is also the softest mineral on the earth.
Talc has a mohs hardness of 1 and an absolute hardness of 1.
9. GYPSUM
gypsum is a naturally occurring mineral of hydrated calcium sulfate with the chemical formula .... Gypsum is mostly found in layers of sedimentary rocks and as deposits from volcanic eruptions. They are used to make fertilizers and it also serves as the main ingredient in different forms of plasters, chalks and cement.
Gypsum has a mohs hardness of 2 and an absolute hardness of 2.
8. CALCITE.
Calcite is a pure form of calcium carbonate(...) that serves as a principal constituent of other minerals such as limestone, chalk, and marble. They are found in all sedimentary, metamorphic and igneous rocks and it one of the most common mineral on the earth.
Calcite has a mohs hardness of 3 and an absolute hardness of 14.
7.FLUORITE
Fluorite or fluorspar is a naturally occurring mineral of calcium fluoride(..). It mostly unique in it variable color spectrum, existing as blue, black, purple, brown, pink, green, etc. Fluorites are formed mostly in by the hydrothermal activities of igneous rocks and limestone.
Fluorite has a mohs hardness of 4 and an absolute hardness of 21.
6. APATITE
Apatite is a general name given to a group of phosphate minerals which possesses similar chemical composition and physical structure. They contain elements like fluorine, chlorine and hydrogen existing as fluorapatite, chlorapatite and hydroxaptite and having a high concentration of OH, F and CL ions, respectively in their crystals. They're mostly used as fertilizers because of their high phosphorus content.
Apatite has a mohs hardness of 5 and an absolute hardness of 48.
5. FELDSPAR
Feldspar is a general name given to a large group of rock-forming silicate or tectosilicate minerals. Feldspar is the most abundant group of silicate minerals and in turn, it is also the most abundant group of minerals found in the earth's crust, making up as much as 50-60% of the earth's crust.
It possesses the chemical formular ... and just like the apatite group, feldspar minerals have very similar structures, chemical compositions, and physical properties and they can be found in igneous, metamorphic and in most sedimentary rocks.
Feldspar has a mohs hardness of 6 and an absolute hardness of 72.
4. QUARTZ
Quartz is naturally occurring mineral and a chemical compound composed of silicon and oxygen. It is the second most abundant mineral in the earth's crust(second to feldspar) and the most abundant mineral on the earth's surface.
Quartz is the the major building blocks of most igneous rocks like granite, and felsic. It is also very common in sedimentary rocks like schist and gneiss.
Quartz has a mohs hardness of 7 and an absolute hardness of 100.
3. TOPAZ
Topaz is a crystalline mineral of the silicate group, with a chemical formula of .... Topaz is widely used as a gemstone in jewelry and other ornaments. It is the hardest mineral in the silicate group, occurring as crystal pegmatites in silicic rocks such as granite and rhyolite.
Topaz has a mohs hardness of 8 and an absolute hardness of 200.
2. CORUNDUM
Corundum is a very hard natural mineral composed of crystalline form of aluminium oxide with the formula ... It also contains traces of impurities of metals such as titanium, vanadium, and chromium. Corundum is a rock forming mineral found in igneous, metamorphic and sedimentary rocks.
Corundum also exist as two types of gemstones, namely; ruby and sapphire.
Corundum has a mohs hardness of 9 and an absolute hardness of 400.
1. DIAMOND
Diamond is crystalline mineral, composed of a pure form of the element carbon. It is the hardest natural substance ever known to man and also has the highest thermal conductivity than any other substance.
Diamond has a mohs hardness of 10 and an absolute hardness of 1600.
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