material?

Is the loop cast in or added to the piece

It could be any age ... my guess would be a modern charm bracelet or necklace.

Vaguely looks like St. George on horseback slaying the dragon.

Looks like a St. George amulet. The script around the edge looks like archaic Cyrillic, which is still in use in the Russian Orthodox church. So far as I know, St. George is considered a patron saint of travelers and also of Moscow, Russia.

If it's Russian and really old, then it would be pre-1917 (e.g. before the Bolshevik revolution in Russia). It could also be a modern reproduction of an antique original. Russian Orthodox churches in the former Soviet Union sell repros together with modern icons and such. Could also be something from a church that served Russian emigres in Europe during the Soviet period. Could also be from another Eastern European country that uses Cyrillic alphabet.

What does the back look like? That could provide a clue, too.

Does it hold a magnet? And what happens if you wipe a small part with acetone?

If it holds a magnet it's iron or steel. if it looks like it has a coating, it has been painted.
Guessing it's a key fob or something that has been painted gold. Certainly not ancient.

Doesn't look ancient to me either. The female head is vaguely familiar. Perhaps from an Renaissance era painting, but I can't remember for sure. Looks like an amulet type trinket to me.