Modern or medieval? Analysis of an iron anchor from Camuscross, Scotland and direct dating methods for metal artefacts

Radiocarbon dating

“…For the analysis of mortars and plasters, prior to sample selection and radiocarbon dating, petrographic analysis and characterization of their chemical and mineralogical composition using x-ray fluorescence and x-ray diffraction must take place [270][271][272] . Similarly, metallurgic analysis of iron objects and estimates of carbon content precede the dating of pre-industrial iron objects [282][283][284] . Finally, interpretation of results requires a combination of all available information: art history, art analysis or provenance research.…”

Curved Linear Diode Array Imaging of a Historic Anchor Recovered from East Anglia ONE Offshore Wind Farm

“…If the anchor is indeed 16th century or earlier, it should have been made using wrought iron from a charcoal-fuelled process, either bloomery iron as found with the Gresham Wreck bars [6], for example, or refined from cast iron made in a charcoal-fuelled blast furnace. Slag inclusion analysis methodology is currently more accurate than carbon dating, particularly if the iron's carbon content is low [7].…”

“…Chemical analysis of the small inclusions of slag waste left in the metal, from when it was smelted or refined, can also indicate the type of fuel used (charcoal or coke) and so suggest a possible date range [6]. Sometimes there is enough carbon in the iron itself to attempt radiocarbon dating [7]. All these methods require samples to be taken, and as it was agreed prior to recovery that the anchor would eventually go on public display, a non-destructive investigative programme of analysis was developed to try to illuminate the mode of construction and the individual elements that comprise the internal structure.…”

“…Heritage 2024, 7 2554 operated underwater vehicle) on 3 March 2018 determined the object to be a possible anchor and it was assigned an initial 20 m radius archaeological exclusion zone (AEZ). The anchor was located in close proximity to a planned wind turbine generator (WTG) (Figure 2).…”