BROOCH

An incomplete Roman copper-alloy gilded and tinned (or silvered) circular plate brooch (AD 200-350) of Hattatt's gilded glass 'centre-boss' type, missing the pin, spring mechanism and glass centre-boss. The pin lug and the central wall surrounding the missing setting have both suffered post-depositional damage.
The central wall measures 17.0mm in external diameter, 14.8mm in internal diameter and stands 2.3mm high. The circular area within is almost 50% covered with corrosion and has a raised ring 3.7mm in diameter around a perforation 1mm in diameter, at the centre.
The external surface of the wall still carries a thick layer of gilding, which extends to the flat area beyond (4.3mm wide). Beyond this is the lip flanking the outside edge of the plate, 2.1mm high. Just inside the lip and just outside the central wall is a ring each of short transverse incised line decoration.
With the lug at 12 o'clock to the reverse, the lip of the brooch between 7 and 9 o'clock has 10 transverse grooves in two groups of seven and three. There is a further transverse groove at 10 o'clock.
The reverse of the brooch has a white-metal coating of tin or silver, extending over both the incomplete lug and catchplate (although worn from the curl of the catchplate). The lug has broken across its central piercing (1.6mm diameter). There is a raised rectangular area between lug and catchplate.
The brooch measures 27.4mm in diameter, 10.6mm in height (inclusive of lug; without it measures 4.8mm high) and weighs 7.67g.
Plate brooches usually date to the second and third centuries, while 'glass centre boss' types are thought to be slightly later, to the third if not the fourth century (Bayley & Butcher, 2004, p.178).