section_path: Physical properties/Hardness
section_name: Hardness
paragraph_text: Hardness
  
  The hardness of a mineral defines how much it can resist scratching or indentation. This physical property is controlled by the chemical composition and crystalline structure of a mineral.
  
  The most commonly used scale of measurement is the ordinal Mohs hardness scale, which measures resistance to scratching. Defined by ten indicators, a mineral with a higher index scratches those below it. The scale ranges from talc, a phyllosilicate, to diamond, a carbon polymorph that is the hardest natural material. The scale is provided below:
  
  A mineral's hardness is a function of its structure. Hardness is not necessarily constant for all crystallographic directions; crystallographic weakness renders some directions softer than others. An example of this hardness variability exists in kyanite, which has a Mohs hardness of 5 1 ⁄ 2 parallel to but 7 parallel to.
  
  Other scales include these;