The stone hardness is the ability to invade other objects machinery. It is related with stone mineral composition, structure, construction. The stone hardness is usually divided into the relative hardness and absolute hardness.

Relative hardness: 10 kinds of minerals used as a standard, according to the size of the relative hardness, it can be divided into 10 levels. Relative stone hardness had been set by the mineralogist Moore, so also called Mohs hardness. Mohs hardness does not have a strict quantitative criteria, and therefore less in the performance of the stone used, but because the Mohs hardness easy to use, so in the absence of special equipment used to roughly determine the type of rock or mineral species. Such as iron Mohs hardness of 5 to 5.5, so the knife can not be carved in granite signs, and the hardness of marble in most of the marble is less than 4, can be carved by a knife, so using the knife can be distinguished rock belongs to categories.