Expert: Ralph Salier - 9/17/2009

Question
how does wearchaeologist use chemistry?

Answer
Hi Tatiana,

Archaeology uses chemistry in several ways.  First of all, in dating objects.  This is one of the more important uses of chemistry we use.  Another is to separate different material fractions.  Many soils have colloids and these stick to every thing.  These are chemically removed and this t hen allows us to look at micro artifacts or biologicals.  Among the biologicals are pollen grains, tiny fish scales, tiny bones etc... These are often found in the flotation fraction of a washed sample.  Next are soil samples that can be used to understand the erosional patterns of the site.  By having the chemistry of the soils analyzed, a "finger print" can be developed and this can then help to identify where these soils came from.  

Ceramics can be analyzed chemically to determine how they were made.  The remains of fires and the fire pits can be chemically analyzed and in some places where materials were stored in clay jars, using chemistry, these substances can be determined.  For instance, amphora (clay jars made around the Mediterranean) found in a ship wreak were found to contain wine, olive oil, and spices.  Most had escaped through the clay but the spices (which had rotted) were still in the jars.  

With stone tools of certain kinds over time, they develop a "crust".  These materials have hydrolized and this can be analyzed for thickness and this can be used to "date"  the artifact.  This is because this layer of material will occur over a timed period which can be chemically determined.

Thus Chemistry is used in many ways for many purposes both in the lab and in the field.