Mohs’ Scale of hardness (also seen as Mohs Hardness Scale, Mohs Scale, or even erroneously as Moh’s Scale) was invented by German mineralogist Friedrich Mohs (1773–1839). This arbitrary scale measures hardness or the scratch resistance of minerals and is often used as a quick way to help identify minerals in the field and laboratory. But the numbers assigned to the various minerals are not proportional to their actual scratch resistance. Thus, the main reason for using the scale is to know that a mineral with a lower number can be scratched by a mineral with a higher number.