Minecraft Java Edition – Why Can’t Diamond, Gold, or Redstone Ore Be Mined?

I'm always mining on the second level on top of bedrock. That is 4-6 blocks on top of bedrock layer.

This area is very rich in everything. Tons of coal, tons of iron and reasonable amounts of gold/diamonds/lapiz/redstone.

I've done some number crunching and I think I have your answer for you. These numbers assume that (a) you use the mining method in the accepted answer you link, (b) that the ores are uniformly distributed, and (c) that you're running a version of Minecraft between 1.6.0 and 1.7.3 (the chart you link hasn't been updated for 1.8 yet).

Mining for an hour with ~30 iron picks should yield you:

• 7,201 cobblestone
• 77 coal
• 308 redstone
• 46 iron
• 8 gold
• 8 diamond
• 37 lapis lazuli

Similarly, using ~6 diamond picks should get:

• 9,166 cobblestone
• 98 coal
• 392 redstone
• 59 iron
• 10 gold
• 10 diamond
• 47 lapis lazuli

As you can see, the iron and diamond yields are far below what goes into the picks. In other worlds, through solid stone, you operate at a loss. Caves make an enormous difference when it comes to mining efficiency.

(All this, of course, assumes my math is correct. Feel free to double-check my work in the spreadsheet.)