It's a cicada.

Sorry, I don't know anything about pre-Columbian artefacts, but I'm sure someone else here will be able to tell you more about its date. It looks very nice to me.

One of the things that interests me is how close a resemblance there is between it and the jade (and sometimes glass) cicadas that were produced during the Han dynasty (two thousand years ago) in China. They had a ritual purpose in burials and were placed on the tongues of the dead (attached is one of the more beautiful I've seen - in the British Museum). It would be interesting to know if they had a similar function in any pre-Columbian culture.

Cheers,

Will