The organic component — primarily collagen — is subject to microbial degradation, hydrolysis, and the slow infiltration of organic compounds from surrounding soils.

For radiocarbon dating, the organic fraction is generally preferred over the mineral fraction because the mineral fraction exchanges carbonate carbon with the environment in ways that are difficult to control.

If the groundwater through which the bone has been sitting contains old carbonate carbon — dissolved from ancient limestone, for example — the bone mineral will incorporate that old carbon and produce an artificially old date.

Conversely, if the groundwater is rich in recent organic carbon, it can make bone mineral appear younger than it is.