BROOCH

Roman copper alloy brooch of Colchester derivative, Polden Hill (Mackreth 2011, Part 3, Group 4.a-b., flat wing ends type), and of 1^st century AD date.

The brooch is fragmentary and represented by the head and upper bow only and would have been comparatively substantial (with a surviving length of 37.8mm, a surviving depth of 17.5mm and a weight of 14.0g). The missing spring was likely to have been secured between lateral lugs now lost. There is the stub of a corroded lug on the head, suggesting that the brooch employed a Polden Hill, lug Type arrangement. The wings are heavily truncated, only partially surviving on one side (with a width of 19.5mm and a surviving length of 5.1mm). Curved mouldings are discernible on the sides of the head (with a width of 14.5mm) and lug on the head to tension the chord, appears to have developed into a decorative midrib. A column of punched rings are discernible on one side of the upper bow but all other detail has been lost. The upper bow is of sub-triangular to D-shaped section with straight sides converging towards the break (where the bow has a width of 8mm and a thickness of 7.5mm). The brooch has a burnt clay core of casting material with a comparatively thin copper alloy skin (1mm thick). The core is circular at the break on the bow (with a diameter of 5mm) and is also evident within the head, behind the missing spring. The copper alloy is heavily corroded with a pale-green patina and areas of bright green corrosion.

The fragmentary nature of the brooch makes typological identification uncertain but the form is consistent with Polden Hill brooches of late 1^st -early 2nd century AD date. The casting involving a clay core is an interesting feature in the brooch and is difficult to parallel. The casting would have involved a high level of expertise and is likely to have resulted in a considerably weaker brooch. The advantages of casting around a core are not immediately obvious, beyond achieving a lower weight for what would have been a comparatively large brooch.