VeinMiner is a mod which lets you mine multiple ores at once. Simply activate VeinMiner mode and any time you try to mine a vein of ores they will all be destroyed at once. It surely makes mining more effecient.
How does it work?
Begin by finding multiple ores that's connected to each other. Then equip a (diamond/gold/iron) pickaxe. Tap on the V button in the bottom-right corner before mining one of the ores and all of the connected ores will be mined as well. It can break up to 128 connected ores.