The Moh scale of mineral hardness is a scale used to quickly estimate the hardness of a mineral. The Moh scale works by charectorizing a mineral by that mineral's resistance to scratching by a harder or softer mineral. 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 a mineral is scratched by quartz, but not by topaz, its hardness on the Mohs scale would fall between 7 and 8.