Nubby black knit cardigan

Purchased this one in a boutique and have no real information about the fabric. It feels like a nubby, cotton knit. It feels really good like natural cotton. There is no size, but I would call it a medium. 3/4 length sleeves and cropped to meet the waist. It works perfectly over a spaghetti strap dress or cami. Tie it at the neck or leave it open. There are no buttons.