Fluorine Dating

A relative dating technique used on bone. Bone absorbs fluorine from groundwater at a rate proportional to the time since burial - if groundwater migration rates remain constant. Fluorine concentrations are chemically analyzed by the gradual combination of fluorine in groundwater with the calcium phosphate of the buried bone material. Bones from the same stratigraphical context can be dated relatively by comparison of their fluorine content. The Piltdown forgery was finally exposed by this method.

One of the methods of bone dating. Fluorine-containing groundwater percolates through deposits, its fluorine becoming absorbed onto the crystal lattice of the mineral component of buried bones (in the same way that fluorine is adsorbed into the surface layers of teeth from repeated brushing with fluoride toothpaste). Given a constant rate of groundwater percolation, the concentration of fluorine in the bone should be proportional to its age. Bones from the same stratigraphical context can be dated relatively by comparison of their fluorine content. The Piltdown forgery was finally exposed by this method.