Xanadu

Mass Effect
Xanadu's atmosphere is composed of methane and argon. Its frozen surface is mainly composed of potassium with deposits of calcium. Its location in the deep cold of the outer system and its lack of any valuable resources leave little to recommend it.

Mass Effect 3
Xanadu's atmosphere is composed of methane and argon, while the planet's frozen surface is largely potassium with deposits of calcium. Its location in the deep cold of the outer system and the lack of resources leave little to recommend it.