There's more than just one artifact actually, so telling you where they are is a matter of looking around for chests that are gold and green. There is one in the camp east of Cedar if you want to check there, and another in the fairy forest to get ya started. From there, just explore around and keep an eye out. You'll find more in no time.
BTW, there are known like 6 or 7 artifacts presently, and Alice will sell ya them and give you the recipe for crafting them on a whim.