The Veinminer mod is an incredible time-saver when mining for ores. It breaks every ore block touching the one that you mine first. So if you come across a seemingly endless vein of coal, this mod will do all the leg work with just one block broken. It has 3 modes: Auto, Sneak, and No_Sneak. Auto activates the mod with a keybind press (by defaut ‘~’); Sneak activates while sneaking; and no_sneak is just always on.
This mod is also customizable within the config file. You can change which tools can break the ores in bulk and also what types of ores. Even better is the mod follows the rules of enchantments so if you have an enchanted pick the blocks will break according to what the spells allow.