File:Anglo saxon brooch (FindID 460435).jpg

English: Circular base silver disc, thickly gilded on the front and in excellent condition, with a silver rivet through the centre. The disc measures 41mm in diameter and 1.2mm thick, and is slightly convex. It has a reserved border decorated with circular punchmarks, which merges into a wider reserved central cross with similar punchmarks. At the centre of this cross is a reserved but not punch-marked circle, in the centre of which a separate shiny silver dome-headed rivet is fixed (diameter 5.7mm). The four panels thus made are sunken and have chip-carved counter-relief interlace, subtly different in each quarter. The interlace is net-like and occasionally expands to form small triangles which are sometimes decorated with a single, or in two cases three dots (the three dots occur in diagonally opposite quarters). The interlace is in each case abstract, with no animal elements identifiable.

Two opposing arms of the reserved cross are interrupted by circular rivet holes, those at the end of one arm smaller (0.5 and 1.1mm) and those at the end of the other larger (0.8 and 1.5mm diameter). The holes are set in a slightly irregular fashion but the smaller holes in both cases are towards the edge of the disc.

The reverse of the disc is undecorated and is covered with a thick layer of copper corrosion, but in patches the underlying surface is visible and this looks very much like silver (see analysis report below).

The placing of the peripheral rivet holes indicate that this disc is likely to be part of a brooch with a one-piece pin and catch fixed with the rivets. This means of attaching the pin is fairly common in the 8th and 9th centuries, with examples known from Evington Brook, Leicester and from the Pentney hoard (Webster and Backhouse (eds) 1991, nos. 186-7). The ornament has links to that on the Witham linked pins, with the dotted reserved bands and the dotted triangles (on the Witham pins extended into animals) seen on both. These parallels date the Nassington disc to the late 8th century.

Similar examples of brooches on the PAS database include NCL-771FB5 (also with a separate silver rivet), WMID-054B67 and DENO-EF72B3. The ornament can also be paralleled on middle Anglo-Saxon pin heads such as NMS-71CF44 and NLM-028751.

This object was originally reported as treasure under the 1996 Treasure Act under the guidance of Dr. Helen Geake. See the Treasure Act Code of Practice, which says that "where an object is made up of distinct components, only one of which is precious metal (for example, a gold binding on an amber object), the components will normally be treated as individual, associated objects." The rivet, if found by itself, would be reportable as Treasure, should it be recognised as over 300 years old. In this case, the rivet is dated by its context within a middle Anglo-Saxon object, and thus the object as a whole becomes treasure.

While at the British Museum, examination of the silvery patches on the reverse suggested that both components of the brooch should be analysed for composition. The report is as follows:

"Non-destructive X-ray fluorescence analysis of the corroded surface of a chip-carved disc from Nassington, Northamptonshire, indicated that the disc is of base silver with approximately 28% silver detectable in the corrosion products, the other elements present in the green corrosion being copper, tin, lead and zinc. The front of the disc is mercury gilded and the central rivet is of good quality silver: approximately 93 % silver, 5% copper and a little lead and gold. The disc weighs 10.08 grams." (S. La Niece and A. Simpson, Department of Conservation and Scientific Research, The British Museum. File no. 7474 79, 5th October 2011).

Both components of the object therefore count in their own right as Treasure, as both are over 10% precious metal and more than 300 years old.