Minecraft wiki entry for Mining, associated text: Never take valuable items when going mining. The player don't want to delve into dangerous caves while carrying tons of iron and diamonds, for if they lose them while mining, they will be sorry. Carry more supplies for longer trips, but don't carry more than they can afford to lose to lava. Normally, they will want to use stone pickaxe for economy, but carry at least one iron pick for advanced ores (gold, redstone, and of course diamond). If they have tons of iron and are impatient, they might use iron pickaxe in general, but while those are faster, they only last twice as long (block-wise) as stone tools, and they will be going through a lot of pickaxe regardless. Take a diamond pickaxe if they want to be fast and efficient for its durability, or to collect some obsidian. Make sure to bring a sword, or at the very least, a bow and some arrows.