Globally non-uniform ore distribution

Exploring caves in Minecraft is amazing, but once you start digging tunnels or strip mining, monotony sets in. Any given 32x32 area on the map, if fully mined out, will yield pretty much the same sampling of coal, iron, gold, lapis lazuli, redstone, and diamonds as any other 32x32 area. This means that the choice of where to dig is mostly meaningless&mdash;you can build pretty much the same "mine" anywhere and expect similar results. Similarly, once you finish mining out one contiguous vein, there's usually no reason to focus your exploration on that immediate area; you're as likely to find more of the same ore next to it as you are anywhere else.

The Globally non-uniform ore distribution mod (concept) aims to change that.

Concept
Borrowing from real world minerology, a simplistic geological simulation distributes high and low concentrations of each ore to distinct locations. A mountain may swell atop the world's largest coal deposit, with hardly any gold or diamonds; a distant ravine may expose a massive vein of gold running for several hectometers; a spike of iron ore rising from a lake may be a sign of a much larger ferrous treasure beneath.

This means that once a player finds ore, they have a reason to dig out a larger part of the surrounding area to see if there's more; and if they do find more, they'll have a reason to settle down and built on that spot, for future access to that resource. Over time, players would accumulate resource-specific settlements in different locations, visiting each as needed.

Finding ore
It should be pretty fun to build a mining complex once a rich area is found, but searching for them could be even more monotonous than the status quo if it's purely random, so players should have some reasonable way of tackling this challenge.
 * Noticeable surface features as a telltale for the alert explorer
 * Exposed ore for coal and iron
 * More subtle geographical patterns like unusually shaped hills, valleys, and rivers for higher value ores
 * Recommend Industrialcraft's ore scanners
 * Certain hostile mobs could be associated statistically with certain ores; for example, creepers might be a sign of gold or diamonds nearby
 * Caves might be distorted to expose or conceal certain ores

On the other hand, it would make sense to retain at least some sense of "luck" to make a big find feel that much more special.

Terrain Features Associated With Ore Veins

 * Coal
 * Mountains & Hills (ie traditional coal seams)
 * Thin layers under swamps (peat bogs)


 * Iron
 * Extreme Hills & Mountains (banded iron formations)
 * Small deposits in lakes, swamps and around springs (bog iron)
 * Small veins associated with lava pools (igneous veins)


 * Gold
 * Deep veins, associated with iron igneous veins
 * Rare veins in mountains and ravines
 * Rivers - dirt & sand blocks in river biomes have a very small chance of dropping gold nuggets when mined.


 * Diamonds
 * Igneous deposits only - spawn in small veins next to and around lava pools


 * Redstone
 * Um, how about if Redstone only spawns as crystal formations in caves?

Modded ores
We should allow other mods to integrate their ores into the distribution scheme (for example, if this mod is installed alongside Industrialcraft, the map would have copper- and tin-rich areas). Depending on how the map generator works, we might do this directly inside the vanilla engine, or we might have to provide an API for mods to register their ores. The latter would probably be best, because it would allow mod authors to specify the value of their ore and whether it should have surface telltales.