The fishshaped jade ornament is an important category in the history of ancient Chinese jades. Prehistoric fishshaped ornament jades have seldom been unearthed in China. However, a fishshaped ornament from the Hongshan culture was found at the Nasitai Site in Bairin Right Banner, Inner Mongolia.The material used to make this object is a matter of debate because there is little scientific data available. Portable Raman spectroscopy and portable Xray fluorimetry were used to determine the jade composition of the fishshaped ornament. These studies suggest that the ornamentis composed of fluorite. This is the only jade from prehistoric northern China determined by scientific methods to be fluorite. The results in comparison with several reports on fluorite jades unearthed from prehistoric sites in southern China were discussed .The discussion is mainly on the material and the shape and carving techniques.