Archaeology dating metal dating acuracy
This Note describes a series of characteristics that can be evaluated to distinguish different metals.The most common metals found on archaeology sites are cast and wrought iron; copper and its alloys (brass, bronze); lead, tin, and their alloys (pewter, Britannia metal); and zinc (either in the form of plating or alloyed with copper or lead).
white metal on a copper cooking pan is most likely tin. Corrosion products can form as thin, coherent layers or thick, disfiguring crusts which obscure the details of the object.
In soil with a high phosphate content, vivianite (blue iron phosphate) can form on iron.
A burned iron object may have a layer of deep red haematite (iron oxide) directly over the metal.
Therefore, identifying an artifact and knowing its function can assist in identifying the metal(s) present.
For example, cast and wrought iron can be difficult to distinguish, but knowing the purpose of the artifact can assist in identifying which type of iron is present.
Although it is not likely that specific alloys can be distinguished in a field situation, it is usually possible to sort artifacts according to type of alloy.