| Answer | Crossword Clue |
|---|---|
| TIN | It measures 1.5 on the Mohs scale |
| APATITE | 5 on the Mohs scale |
| OPAL | It's 6.5 on the Mohs scale |
| APATITE | It's 5 on the Mohs scale of hardness |
| OPAL | Stone measuring 5.5 to 6.5 on the Mohs scale |
| THATSREALLYHARD | "Bonus question in Science: What does a rating of 10 on the Mohs scale represent?"...BZZZT... "Noramus for 5 points!" |
