Unique ID: 77
The Duro Thunderbolt quarter staters were minted by the Durotriges sometime between 50 BC and 40AD. They are a continuation of the boat and geometric theme started by the Morini tribe with their GB-Ca2 and GB-D quarter staters. By the time the Durotriges minted these they had run out of precious metals, so these are made from a low quality billon alloy containing no gold and almost no silver. They would normally be classed as silver units because of their size, weight, and thickness, but they are quarter staters because the entire Durotriges monetary system became highly debased (they eventually struck, and then cast, staters in bronze), and inflation would have caused the lower denominations such as silver units to be abandoned, leaving just staters and quarter staters, and ultimately just staters.
It can appear tricky to tell Duro Thunderbolts apart from Badbury Rats (ABC 2214; see 10 and 23) because all the major features such as the thunderbolt, clamshell, ringed pellets, dotted lines and the rat can be present on both. The key difference is that the thunderbolt chages direction. On the Badbury Rat coins the top is to the left of the bottom, but on the Duro Thunderbolt coins, the top is to the right of the bottom.