A calibration curve can be produced by measuring standard solutions of known fluoride concentration.
The resulting fluor-apatite is more stable than the original form, thus the fluoride content of a bone will increase over time if it is exposed to a solution containing fluoride ions.Fluoride ions are present in trace amounts in most soils and groundwaters.Over time, buried bones pick up fluoride ions from soil moisture or exposure to groundwater.Older specimens have higher fluoride contents than younger ones when burial conditions are identical.The requirement of identical burial conditions means that fluoride dating works best when it is applied within a single site with little variation in soil chemistry.Many different techniques can be used to measure bone fluoride content, but measurement by ion selective electrode is the easiest and simplest method available today.
The fluoride selective electrode uses the same principle as the familiar p H electrode.
When the electrode is placed in a solution that contains fluoride, it produces a voltage that is proportional to the amount of fluoride in the solution.
Fluoride (or fluorine) dating is a relative dating method that can be used to date archaeological bone.
As a relative dating method, it can determine the relative age of specimens, but cannot provide a calendrical date unless the fluoride chronology is calibrated with an absolute dating method.
Bones are primarily composed of the mineral calcium hydroxy apatite.
When exposed to water that contains fluoride, a fluoride ion (F-) can replace a hydroxyl ion (OH-) in the bone mineral.