Large Black Pottery Jug / Vase, Presumed South American

I honestly know nothing about this vessel, other than that I think it has a great silhouette and an interesting surface, rough in spots and with a greenish tone that make it feel rather ancient. I purchased it at the estate sale of a family of artists who had many wonderful things, including some terrific Ecuadorian textiles and ceramics. That and the jug-type shape make me assume it is South American. I'd love it filled with a a couple of tall flowering branches or a few huge Asiatic lilies. 7" tall x 8" wide, and 2 3/4" across at opening. Great vintage condition, no chips or cracks.