The ores which are generated to look like the surrounding UB-stones can be configured through the JSON-files in the [minecraft_folder]/config/undergroundbiomes/ores-folder. Each JSON can have as many ores as it wants to, it is recommended to create a JSON-file for each mod, named after the mod without spaces and in lowercase. This will prevent crashes when updating to a new version which may add defaults for said mod. Beware that trying to register the same ore twice, will crash the game!

Genreal Information on JSON can be found on json.org or Wikipedia

An example of a simple json file with two ores:

[
  {
    "internalOreName": "minecraft:diamond_ore",
    "meta": -1,
    "overlay": "undergroundbiomes:blocks/overlays/minecraft/diamond",
    "oreDirectories": ["oreTest", "someOre"],
    "alphaOverlay": false,
    "color": "#358b95"
  },
  {
    "internalOreName": "minecraft:iron_ore",
    "meta": -1,
    "overlay": "undergroundbiomes:blocks/overlays/minecraft/iron",
    "oreDirectories": ["oreIron"],
    "alphaOverlay": false,
    "lightValue": 0
  }
]

You can add as many of these {}-blocks as you want, beware that you need a , between them and none after the last block!

Each ore has the following attributes:

• internalOreName: The name under wich the ore is registered with forge.
• meta optional: The meta-value of the ore (needed if a mod registers multiple ores with the same registryname). -1 means there is no need for meta-values and is generated with the deafult settinngs, but could as well be omitted.
• overlay: The texture to use for the ore. The part before the : is the name of the mod containing the texture, the part after the : is the path to the texture from the mods textures-folder. For Underground Biomes those textures can be found in blocks/overlays.
• oreDirectories optional: A list of ore-directories to add the generated ores to. This depends on the context of mods you are using. The ore-directory-entries of the original ore should be copied to the generated ores, this might help if it fails (see #11). Can be removed if no additional ore-directory entry is needed.
• color optional: A hexadecimal representation of a color. The color will be "multiplied" (mixed) with the selected texture. If you want a clean color I provided some uncolored textures in the custom-directory: every file starting with ore (colorless versions of the Minecraft ores (ore2 is lapis lazuli)) and gem.png (colorless emerald overlay).
• lightValue optional: The light level emitted by the ore. Valid values are numbers between 0 (no light) and 15 (as bright as a torch or glowstone). -1 is special and means "let the original ore handle it" (default). Needed for NuclearCraft ores.
• alphaOverlay optional: If the overlay contains alpha (or semi-transparents) textures. true if yes, false if no. Most overlays should be using false.