Rare lead ingot found in Bronze Age hoard – History

A Bronze Age metal hoard discovered near Dereham, Norfolk, in 2019/2020 contained three rare lead ingots. These objects date back to the Late Bronze Age. 950-800 BC, which is also the period when the treasure was stored.

The hoard includes four holed ax heads, fragments of an ax blade, a holed carpenter’s chisel, fragments of a sword blade, fragments of a bun ingot and three rectangular lead ingots. Most items were damaged or missing parts and were likely buried for safety before being melted down and reused. This chisel is the only piece of bronze still intact at the time of burial. Perhaps it has reached the end of its useful life and is destined to be recycled.

The lead ingot is the real mystery ingredient in the mix. Lead is an essential element in bronze casting alloys, and its proportions continued to increase by the late Bronze Age. However, objects made entirely of lead are extremely rare, and even rarer are found lead ingots. Some of the lead artefacts in the Late Bronze Age hoard were thought to be raw material – a flat, irregular piece of casting waste – but a deliberately shaped rectangular cake like this had never been found before.

“The protagonist is what makes people excited about this particular treasure,” said Dr. Wilkin, curator of the museum’s Early Europe (Neolithic and Bronze Age collections).

The reason is that some 3,000 years ago, Bronze Age metalworkers worked out the best recipe for casting bronze. He explained that the elemental mix contains just under 90 percent copper, about 10 percent tin, and between 1 and 2 percent lead.

“This may seem like an insignificant amount of lead, but if you talk to people who experiment with bronze casting today, they will say that lead has a big impact on the melting point of bronze and its pourability in complex molds,” he said.

Some Late Bronze Age axheads contain up to 15% lead, so the need for raw materials may have been greater when these treasures were buried, but with no known similarities, the function of the ingots is unclear. They may of course be added to the alloy when recyclables are melted down to increase their lead content. However, given the extreme rarity of Bronze Age lead ingots in the archaeological record, they may have had other uses.

Dr. Wilkin speculates that the site of Dereham’s discovery may also have been a trading post because of its proximity to the North Sea.

“There is a lot of evidence that this was a fairly specialized craft and that the blacksmiths were probably mobile and probably traveled to several different communities creating tools for them,” he added.

The hoard is currently being assessed to determine whether it qualifies as a treasure under the UK Treasure Act (it does; the outcome is a foregone conclusion). Once it is declared a treasure, a valuation committee will determine its market value and the museum will have the opportunity to acquire it in exchange for the total price. timeThe British Museum has expressed interest in acquiring the treasure.