BY JIM BRACE-THOMPSON

The Mohs Scale of Mineral Hardness turns 200 this year. Here’s why it’s still important today.

WHAT IS THE MOHS SCALE?

The Mohs Scale is a tool to help identify minerals based on their hardness compared to 10 selected minerals. It is based on the observation that one mineral will scratch another mineral but not vice versa. Diamond (the hardest mineral) easily scratches talc (the softest mineral), but talc will never leave a scratch on a diamond.