Editing Radiocarbon dating (section)

===Material considerations===
* It is common to reduce a wood sample to just the cellulose component before testing, but since this can reduce the volume of the sample to 20% of its original size, testing of the whole wood is often performed as well. Charcoal is often tested but is likely to need treatment to remove contaminants.<ref name=Bowman_27/><ref name=AitkenWashing/>
* Unburnt bone can be tested; it is usual to date it using [[collagen]], the protein fraction that remains after washing away the bone's structural material. [[Hydroxyproline]], one of the constituent amino acids in bone, was once thought to be a reliable indicator as it was not known to occur except in bone, but it has since been detected in groundwater.<ref name=Bowman_27/>
* For burnt bone, testability depends on the conditions under which the bone was burnt. If the bone was heated under [[reducing conditions]], it (and associated organic matter) may have been carbonized. In this case, the sample is often usable.<ref name=Bowman_27/>
* Shells from both marine and land organisms consist almost entirely of calcium carbonate, either as [[aragonite]] or as [[calcite]], or some mixture of the two. Calcium carbonate is very susceptible to dissolving and recrystallizing; the recrystallized material will contain carbon from the sample's environment, which may be of geological origin. If testing recrystallized shell is unavoidable, it is sometimes possible to identify the original shell material from a sequence of tests.<ref>Šilar (2004), p. 166.</ref> It is also possible to test [[conchiolin]], an organic protein found in shell, but it constitutes only 1–2% of shell material.<ref name=AitkenWashing/>
* The three major components of peat are [[humic acid]], [[humins]], and [[fulvic acid]]. Of these, humins give the most reliable date as they are insoluble in alkali and less likely to contain contaminants from the sample's environment.<ref name=AitkenWashing/> A particular difficulty with dried peat is the removal of rootlets, which are likely to be hard to distinguish from the sample material.<ref name=Bowman_27/>
* Soil contains organic material, but because of the likelihood of contamination by humic acid of more recent origin, it is very difficult to get satisfactory radiocarbon dates. It is preferable to sieve the soil for fragments of organic origin, and date the fragments with methods that are tolerant of small sample sizes.<ref name=AitkenWashing/>
* Other materials that have been successfully dated include ivory, paper, textiles, individual seeds and grains, straw from within mud bricks, and charred food remains found in pottery.<ref name=AitkenWashing/>