What it does
Power 15 (Uncommon), about 4x the Power of the Stone Pickaxe.
How to get it
Pickaxe Shop in the Safe Zone for $800. There's also a Robux button.
Pro tip
Get it before you move to the Desert (1K Speed). Robux shortcut: Pickaxe Tier 3, 29 R$ (tier match is our best guess).