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Beta Analytic Q&A: Is it Possible to Date Fired Clay Bricks?

July 1, 2013

It is possible to date fired clay bricks, but it depends on how the bricks were manufactured and what types of contamination may have been absorbed into the bricks since they were put in place.

We recommend sending 2-10 grams for AMS dating.

Dating fired clay brick is much like dating pottery sherd. Sometimes it is possible to extract small amounts of organic materials like straw, twigs or charred material from the clay. This is the best way as we can date materials that were short-lived, and we can give a full range of acid and alkali treatments to remove both carbonate and humic acid contaminants. If these materials are not present, then we can attempt the dating of the “bulk organic fraction.”

The bulk organic fraction is composed of the organic materials from the original clay and any organic substances that have taken up residence in the clay since its manufacture. This is a less accurate way of dating but, depending on the type of materials used in brick construction and what any secondary contamination the bricks have been exposed to, the results can many times be quite useful.

When dating the bulk organic fraction, it is best to have other lines of evidence to evaluate the result with. Bulk organic fraction dates may tend to yield results that are somewhat more recent than the actual date as there may be more recent humic acids that have taken up residence in the bricks since installation. In rare instances, the results are too old but this is only when the clay used was dug up from some depth, thus the organic materials in the clay were already hundreds to thousands of years old at the time of manufacture.

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