Here is the full list of all 49 Grindstone achievements.
Use the OK Boomerang over lava
Unlock all other achievements
Complete 3 Creep hideouts
Complete a level with any 3 pieces of gold gear and the Grindstone Garb
Complete a level with the Detonator Suit, Fireball Sword, Fire Arrow, and Firewalker Potion
Complete a level with the Ranger Outfit and any 3 arrow types equipped.
Complete a level with the Vine Sword, Poison Arrow, Poison Shield, and Plague Doc Outfit
Mine gold using the Goldrush Garb and Pickaxe
Dodge 3 attacks with the Gladiator Outfit
Complete a level with the Spinny Sword, Arrow, and Pickaxe
Make a Jerk melee another Jerk
Survived Jjary, again (and again and again)
Defeat MjeatBöll
Defeat Jjurk-Creepethuth
Complete a Quick Grind without dying
Complete a Greed Grind without dying
Defeat MekkaMortie
Collect 50 magma rocks
Kill 200 Jerks
Collect 50 crowns
Collect 50 ice
Cause a Jerk to die from poison
Defeat Creepzïlla
Collect 50 poison mushrooms
Collect 50 Vine Hjeart seeds
Collect 50 gold
Kill 50 Slobs
Create a 45-Chain Grindstone
Kill 10000 Creeps
Eat 3 of Helgä's snack items
Start a level with only 1 heart
Wake up in the Inn
Collect 50 iron
Defeat SkjellyKjing
Collect 1000 grindstones
Collect 50 ectoplasm
Collect 50 guts
Collect 50 bones
Collect 50 batwings
Kill 1000 Creeps
Collect 50 wood
Kill 20 Jerks
Complete a Fortune Grind without dying
Complete Level 1
Survived your first boss
Create a 15-Chain Grindstone
Create a 30-Chain Grindstone
Spare a Royal Slob
Kill 5 Slobs