Pickaxe
Upgrade your pickaxe as soon as you can. It is critical for progressing through the game. This is a Mining game, after all!
A higher tier pickaxe will mine through harder dirt, and it will mine faster in general. The most coveted ore is deep inside the mine, and you'll need a strong pickaxe to get there!
Stronger pickaxes also deal more damage if you use your pickaxe in combat, although they don't make the best weapons.
Steel Pickaxes aren't the end of the line for your Pickaxe upgrades though. You can keep progressing through stronger pickaxes until you've found them all!
The Worms you'll find in the mine have teeth harder than steel. You can use them to make a better pickaxe! After you've already purchased your Steel picakxe, you can bring several Worm Teeth to the store to make a better pickaxe. Teeth from the Snow Worms work just as well, so you can hunt for worm teeth above or below ground when you're ready for this pickaxe upgrade.