Samples, Aliquots, and Specimens

The archaeological chemist samples what is available. For example, there are thousands and thousands of pottery fragments, or sherds, at many archaeological sites. It is simply not possible to select a specific fraction of the sherds to analyze. 

The most commonly used term for a piece of material that is analyzed is sample. The word is used in many ways in archaeology and archaeological chemistry. A sample is a part of a larger quantity selected for analysis, but is not necessarily a fixed quantity. For our research on tooth enamel, we use the first molar from the lower jaw of a human skeleton. In one sense, the tooth itself is a sample (Fig. 1.7). We then take a sample of the enamel or crown portion of a tooth. Initially that means roughly 0.1 g of small flakes and powder from the tooth. After some cleaning and other preparation we weigh out a 5 mg portion for analysis. That 5 mg part is also a sample of the tooth enamel. 

Aliquot is a more specific term, used less commonly in archaeological chemistry. Aliquot refers to an equal, measurable part of a large whole. For example, an aliquot of 5 ml of HCl (hydrochloric acid) from a large bottle of acid would be a known amount that could be repeatedly measured out. The term specimen normally is used to refer to units of a population and is often applied to biological materials. A frog could be a specimen for a study of the ecology of amphibians. The term specimen is not commonly used in archaeological chemistry. 

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