What kind of material is radiocarbon dating used on
In short, unless you have evidence to the contrary, you should assume that most of the carbon in a fossil is from contamination, and is not originally part of the fossil. The nuclear tests of the 1950's created a lot of C14.Also, humans are now burning large amounts of "fossil fuel".
The second kind are datings on contaminated samples, or on samples which are a mixture.If you hear of a carbon dating up in the millions of years, you're hearing a confused report. Second, they rarely contain any of the original carbon.We can't date oil paints, because their oil is "old" carbon from petroleum. And third, it is common to soak new-found fossils in a preservative, such as shellac.When this was first done, it turned out that carbon dating had been giving too-young dates for early civilizations.Apparently, the production of C14 by the Sun has changed by several percent across the last 10,000 years.Historians don't have "right answers" for really old things.
However, carbon dating has done well on young material like the Dead Sea Scrolls, the Minoan ruins, and acacia wood from the tomb of the pharoah Zoser.
It is sometimes possible to match up tree-ring patterns between different trees.
When enough suitable trees are found, living or dead, the matching is completely accurate.
The C14 will undergo radioactive decay, and after 5730 years, half of it will be gone. So, if we find such a body, the amount of C14 in it will tell us how long ago it was alive. The method doesn't work on things which didn't get their carbon from the air.
This leaves out aquatic creatures, since their carbon might (for example) come from dissolved carbonate rock.
As the name suggests, fossil fuel is old, and no longer contains C14.