What is Mohs hardness scale?

Minerologist Friedrich Mohs in 1812 developed a scale to determine the hardness of minerals. He ranked the 10 most common minerals in order of their ability to draw each other. Mohs assigned the lowest value of the scale to the softest mineral - talc, which can be scratched by all the minerals above the scale. On the top of the scale ranking 10 is diamond which is capable of scratching all the minerals below. The Mohs scale is disproportionate and is currently only used for rapid mineral identification.