Copper

GregTech
Small copper ore spawns at a height of 60 to 120 with a relative frequency of 32 in the overworld, the nether, and the end. Regular copper ore spawns in several large deposits *TODO*.

Thermal Expansion
Found between layers 33 and 46 with a max vein size of eight. Every Public FTB pack that includes Thermal Expansion will use Thermal Expansion as the main ore generation.

Thermal Foundation replaces the Thermal Expansion ores in Minecraft version 1.7 and up.

Thermal Foundation
Thermal Foundation uses the same spawning mechanics as Thermal Expansion.

IndustrialCraft 2
Found between layers 10 and 70 with a max vein size of ten.

Forestry
Found on layers above 32.

Tinker's Construct
Found between layers 4 and 64. In addition to stone ores, you may also find Copper Ore gravel, and Copper Oreberry Bushes.

Flaxbeard's Steam Power
Copper Ore can be found in the overworld at the same levels as Iron. It can be used to create a Storage Block, Plate, and Nugget. Storage Blocks and Nuggets are created the same way as any other. Plates must be created by putting Copper Ingots into a heated Crucible, at which point the molten metal should be poured into a Mold with a Plate Mold. Six nuggets are used in the creation of a Copper Plate, which makes it unable to be used in other mod's recipes requiring their own Copper Plates.

Railcraft
Copper can be obtained in Railcraft through the Poor Ore system implemented in version 9.1.0.0. It can be found throughout most layers in the world. It can be cooked into Copper Nuggets.