Help With Chinese Coin ID

It's a Yuanyou Tongbao, from the reign of Emperor Zhezong, minted from 1086-1093.

http://en.wikipedia.org/wiki/Empero...f_Song_China

Depending on what is on the reverse, it can be worth anything from 2RMB to 25000RMB (a quarter to around 4k), but most of the regular types are around 1, 2 bucks.

**It's also mounted in a very weird fashion... the square is supposed to have the flat part on the bottom, not as a diamond.

There are two basic classes of Yuan You cash coins, based on the style of the lettering. Your style is "running script", like this example. The other class is the more archaic-looking "seal script", like this example.

As you can also see form the coins in the above links, the "usual" state of 1000-year-old coppery-brass coins is to be covered in a green patina. This has been almost entirely cleaned off from your coin (somewhat harshly, judging by the pitting on the raised areas), but the little traces of it left tell me that it's likely that this is a genuine Song Dynasty coin, rather than a modern replica.

I would also speculate that the manufacturer of this artefact did not know Chinese, or they wouldn't have inserted the coin almost completely upside-down.