Mohs Hardness Scale
From Conservapedia
The Mohs hardness scale for minerals has been used since 1822,[1] having been devised by Friedrich Mohs in 1812. It simply consists of 10 minerals arranged in order from 1 to 10. Diamond is rated as the hardest and is indexed as 10; talc as the softest with index number 1. Each mineral in the scale will scratch all those above it as follows:
