Tropicraft adds some pretty cool volcanoes, but as of right now the mod is broken, you have to build a Nether Portal to get home, which is a pain. But hey! The volcano is filled with lava, and black, like RP2 volcanoes.
And if you want some volcanoes that are more loot based, I think Dungeon Pack or Better Dungeons might add a stone volcano coated in ores including diamond, and is filled with lava, netherrack, and spawners. There are also loot chests all the way down.