Ore Official Minecraft Wiki
Obtaining resources from ores is as simple as mining them (this is not the case for iron and gold ores, which must be smelted). Coal, diamond, emerald, and nether quartz ores drop 1 unit corresponding raw materials. Redstone ore drops 4 5 redstone dust, and lapis lazuli ore drops 4 8 lapis lazuli. Note this can be increased greatly with fortune.