The 0.6 world update is coming along well and today I want to talk about what you are going to find below ground more on the ground level and above at a later date.
Ore generation has been completely overhauled and now produces something like this:
We will start at the top and work our way down. Dirt generation has been altered instead of being a single layer every where it is now between 3 and 5 blocks in depth randomly throughout the world.
The ore generation in the current version of the game is lots of little bits of ore everywhere which made hand mining often the best choice as you couldn't really target anything. The aim is to change that and make ores spawn in "veins" that are far less common but much more lucrative.
When ores spawn their are 3 different types for each ore 'poor', 'regular', and 'rich'. Poor ores spawn on the outside of a vein with regular inside of it and rich inside of the regular. When you take a 2D cross section you get the "target" pattern you can see in the coal vein in the top center of the above picture. In general poor gives 2 pieces of ore when mined, regular gives 3-5, and rich gives 6-10.
The world is separated into 5 different "layers" that change as you go deeper. Each layer has its own type of stone associated with it as well as a transition area between where one stone will be replaced by next as you go down.
As you go deeper in the world ores that spawn near the surface will become less common but those that you do find will have a higher proportion of rich ore. For example look at the large copper vein in the lower right that is mostly rich ores.
As you reach the very bottom of the world ores like copper and iron become extremely rare. There will be more ores in the future like Titanium and Tungsten that will spawn down low in the world. Below layer 500 is bedrock it is just to keep you from going too low. You are welcome to try and mine it but it takes no damage from anything and has a million health. I have decided to make bedrock completely flat for now as making it have texture felt unnecessary.
Of course all of this is subject to change, especially the amount of ore in the world, before release.