Minecraft wiki entry for Snow_farming, associated text: Note that the durability on the shovel will go down very quickly: a new stone shovel without the Unbreaking enchantment will break in about 13 seconds after producing 131 snowballs (enough to make 32 snow blocks with 3 snowballs leftover), and an iron shovel will break in about 25 seconds after producing 250 snowballs (enough to make 62 snow blocks with 2 snowballs left over). Unless you have an iron golem farm or plenty of iron, it is recommended to use a stone shovel, because stone shovels dig up snow at the same speed as gold, iron, and diamond, and cobblestone is extremely common and renewable. However, using stone shovels means that they have less durability, so make sure to bring plenty.