scale: A scale for classifying minerals based on relative
Mohs: Inventor of a mineral hardness scale
scale; Talc-to-diamond scale; Hardness scale; Mineralogist
once a year
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. 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, 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. Using these ordinary
materials of known hardness can be a simple way to approximate
the position of a mineral on the scale.
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article "Mohs Scale".