RIC —. Silver denarius, undated A.D. 222 - 235
obv. IVLIA MAMAEA AVG. Diademed and draped bust r.
rev. VESTA. Vesta seated. l., holding simpulum and sceptre.
This type is unlisted in RIC and the reverse type with Vesta seated l. with simpulum (ladle) and sceptre is not known for Mamaea.
This therefore appears to be the hybrid of an obverse of Julia Mamaea with the reverse of a coin of Julia Domna (illustrated below).
(picture: Auktionshaus H. D. Rauch GmbH, Auction New York 2009 (11.01.2009) lot: 126)
Discussion of this coin is available on FORVM`s Classical Numismatics Discussion Board