Here's what that means:

* Mohs Hardness Scale: This scale measures the resistance of a mineral to scratching. It ranges from 1 (softest, like talc) to 10 (hardest, like diamond).

* Pumice's Position: Pumice falls in the middle range, meaning it's harder than a fingernail (2.5) and a copper penny (3.5), but softer than a knife blade (5.5) or glass (5.5 to 6.5).

It's important to note that pumice's hardness can vary slightly depending on its composition and formation.