It looks like a religious medal to me. Maybe the Virgin Mary. If it is, it'll be difficult to date, as they have been made for many years. Your best hope is to find a makers mark, or some other identifying feature. Wish I could offer you a better answer.
I've been to Fatima in Portugal. Those things, or medalions like them, have been sold to any warm body for centuries. Saintly bones and true cross wood slivers before that. Mark Twain had a few comments on the subject in "Innocents Abroad".
What I thought I was saying was that the manufacturer does not sell to the general public,only to their outlets who do sell/give to the general public,i.e.,churches,schools,etc.