Last week, we mentioned how isotopes are created in quartz. One of these isotopes is carbon-14. We can use carbon-14 to tell how old the rocks are by a process called in situ carbon-14 dating.
What is in situ carbon-14 dating? Have you heard of radiocarbon dating? Traditional radiocarbon dating uses atmospherically-produced C-14 found in living things, but our method uses C-14 produced in nonliving things like rocks.
There are three major steps for carbon in getting from quartz to targets for measuring the number of carbon-14 atoms in the sample: extraction, purification, and graphitization.
In extraction, the carbon is removed by heating the sample at different steps to high temperatures. The carbon is released as CO2. Other extraneous gases which are also released during the heating, such as H2O, must be removed. Once the gas is cleaned up, the CO2 is turned into graphite (carbon in solid form). This material can then be pressed into targets for measurement by accelerator mass spectrometry.