Agrippina Senior. Died AD 33. Æ Sestertius (33mm, 22.96 g, 6h). Rome mint. Struck under Claudius, AD 50-54. Draped bust right / Legend around large S • C, countermarked NCAPR. RIC I 102 (Claudius); Pangerl 1. Host coin Fine, c/m Near VF, light brown patina.
From the Ken Bressett Collection. Ex Spencer 1984 @ $50.
This countermark, one of the most common imperial cointermarks, is likely a validating countermark used during the reign of Nero. For further discussion, see Kraay, "The Behavior of Early Imperial Countermarks" in Essays Mattingly, pg. 132ff. The mark indicated that these coins had been examined by a committee and found suitable for continued use in circulation