Gallienus (253-268 A.D.) -  AE Antoninianus - 18.56x19.86mm, 2.42gr
Obverse - GALLIENVS AVG
Gallienus, his radiate head right
Reverse - PAX AVG
Pax standing left, holding olive branch and scepter.

Minted in Rome, between 260 and 268 A.D.
Reference:
Webb, P.H., "Roman Imperial Coinage", Volume 5, Part 1 (RIC), p1??, nr 256K (under sole reign of Gallienus), no officina mark.
Sear, D.R., "Roman Coins and their Values" (RCV Millennium Edition), Vol. 3, p297, nr. 10300, without mint and officina mark.
Cohen, H, "Descriptions Historique des Monnaies frappees sous l'Empire Romain" (C), Volume 5, p413, nr. 727
Seaby, H.A. & Sear, D.R., "Roman Silver Coins" (RSC), Volume 4, p86, nr. 727
Van Meter, D., "Handbook of Roman Imperial Coins", p247, nr 194
Suarez, R., "Encyclopedia of Roman Imperial Coins" (ERIC),  p300, nr.53, var. M5 (B23, O09, R214, T166, M5)
Quality: Fine+