A late 18th century Revolutionary War era powder horn/priming flask with great patina.  
It has a gadroon-carved design that resembles a rope with alternating hollows and rounds on its semi-dome wood cap and a stylized "Bottle Nose" pouring spout which is carved so well that it looks like the pouring spout has been gently squeezed and smoothed down instead of carved.  It is a Pennsylvania horn that is most likely from Lancaster County.
It is 7.5" long.