It is a coin from the Roman Republican era, issued by moneyer A. Postumius A.F. Sp.n. Albinus. Here's a similar coin and attribution from CNG's archives: A. Postumius A.f. Sp.n. Albinus. 81 BC. AR Denarius. Rome mint. Draped bust of Diana right, wearing hair in knot, earring, and necklace, bow and quiver over shoulder; bucranium above / Togate figure standing left on rock, holding aspergillum over head of ox, standing right; lighted altar between them. Crawford 372/1; Sydenham 745; Postumia 7.