Did the droppings have little pointed ends on them? If so, most likely rat droppings. Muskrats have very weak spincters, so their little turds are tapered on the end to keep their spincters from slamming shut.
Seriously though, your description sounds like rat droppings. Mink, and other members of the weasel family will usually leave less defined squiggly type droppings, while the rats are usually more prone to be pellet shapped. Not always of course, sometimes on a big rat toilet the droppings just pile up into a mush of rat poop.