Minecraft Mining Tips
Q: At what levels are the types of rock commonly found?
Q: How deep should I mine?
128: Coal (rare to 131)
64: Iron (rare to 67)
63: Sea Level
32: Gold (rare to 35)
16: Diamond, Redstone (rare to 20)
Therefore, the best layers to dig at are 11-16. When playing, dig down until you find the top layer of Bedrock. Skip the 6 layers above that, as they may contain lava, and mine layers 11-16.