If its a real fractional gold coin it could be worth big bucks. Can you get a pic of the obverse and maybe a size comparison. Judging by the pic it looks to be high gold content.
Checked the ref. book for Calf. fractional coins. It appears from the photo that it may be a prioid 1 1849 half eagle. As appears on page 23 of California Pioneer Fractional Gold by Walter Breen and Ronald J. Gillio second addition