We used the Mohs scale for mineral hardness, which essentially means how deeply a diamond (which is a 10, the highest number on the scale) could scratch into its surface. It’s the most popular of several indicators of hardness, and not necessarily a rank of toughness, which has its own scale.
Check out this quick picture from AlansFactoryOutlet.com of the different metals of the earth, how humans have used them over the years, and how hard they are!

Infographic by: www.alansfactoryoutlet.com