Irish navvies spent years digging for gold in London's streets, but new research suggests they might be better off heading for Cardiff and looking for platinum. The valuable metal is rapidly increasing in the urban environment and is literally being swept up with road dust.
Platinum is used as a catalyst in the catalytic converters found on modern cars, explained Dr Hazel Prichard of the Department of Earth Sciences at Cardiff University. The devices help clean up exhaust fumes, but a small amount of the metal is released over time as well.
"The use of catalytic converters in cars is very recent and so levels of platinum on our roads are likely to increase rapidly," Dr Prichard suggested. She sampled for platinum in road dust taken from roundabouts and road junctions in the city and in mud retrieved from Cardiff Bay and all were found to contain platinum, most of it from cars.
She described the levels as "extremely high", but all things are relative. Levels of up to 125 parts of platinum per billion were recorded, she said, hardly enough to make you rich quick, but certainly much higher than the normal background level of less than one part per billion.
Levels are on the increase, however, and this very rare metal can be mined economically from solid rock at only a few thousand parts per billion, which encouraged Dr Prichard to suggest that city road dust might "soon form a resource".
Her next goal is to predict where the platinum may concentrate in the city. It may be that in a few years, or centuries, Irish workers will genuinely be mining city streets for precious metals.