Coal Nugget is a mining drop obtained when using a pickaxe less than netherite to mine coal ore. 9 coal nuggets can be crafted into 1 coal.
Wooden Pickaxe = 50% chance to drop one nugget
Stone Pickaxe = 1-2 coal nuggets
Gold Pickaxe = 1-5 coal nuggets
Iron Pickaxe = 3-6 coal nuggets
Diamond Pickaxe = 50% chance to drop 5-8 nuggets (otherwise drops coal)