Beta Analytic Q&A: Is it possible to date charred material isolated from metal slags?

Charred material from a metallic slag can be dated, but it is generally problematic on several fronts.

The separation of the charred material from the slag requires the use of very concentrated acids. The concentrated acid has a tendency to dissolve the charred material into very fine “soot-sized” particles, which are rarely able to withstand the normal types of pretreatments (acid and alkali) necessary to ensure an accurate result.

Also many times the charred material found in slag originates from very large “old” trees that were used in the fires for smelting operations. As such, the wood can be several hundreds of years old when it is burned and this old wood (charcoal) ends up in the slag yielding a much older age than the actual time of manufacture. We have seen this several times when working with this type of sample, and it is why we typically don’t recommend this type of material for radiocarbon dating.

Because of the amount of acid required and noxious fumes emitted, we do not perform the separation of the charred material from the slag. We only analyze the charred material sent to us.

NOTE: We don’t typically recommend this type of dating due to the difficulty in extraction and the uncertain accuracy in the results.