ORC8845 Caracalla antoninianus Diana aEF Caracalla, AR antoninianus, (4.60g) Rome Mint, 215 AD, ANTONINVS PIVS AVG GERM Radiate, draped and cuirassed bust right. / P M TR P XVIII COS IIII P P Diana driving biga of bulls left. RIC256e. Near EF, two small green spots of encrustation on reverse. Caracalla introduced this new denomination late in his reign, and it is generally called an Antoninianus, after the name of this ruler. The radiate crown meant that it was valued as a double denarius, though it generally only had the silver content of 1.5 denarii. Its use was continued by many of his successors, and it ultimately replaced the denarius as the regular unit of commerce. Gresham's Law, "The bad money drives out the good." seller (oldromancoins.com)