The Streets are paved with Platinum
Roadside dirt contains one part per million precious metals such as platinum, palladium and rhodium.Quick - Buy Mr Remittance Man a broom, no more big Cats and stuff that goes bang for him, just sweeping The Great Westway....
This is not much lower than the quantity in mineral mines in South Africa, where the content varies from two to ten parts per million.
Rhodium is worth about £90 per gram, meaning the process could bring in a considerable amount of money to local authorities, although it would be a long process to collect enough dirt for one ring.
Ms Murray, from Tarbet, on the shores of Loch Lomond, said: "In an average street, you would have to sweep three kilometres of road for a year to gather up 30 grams of precious metals for a nice ring or pair of earrings."
However, this would be worth about £2,500 to the local authority. "Even recovering relatively minor amounts has a huge value," Ms Murray added.
The precious metal in the dirt comes from catalytic converters in cars, meaning the busier the traffic, the more precious metal is available.
Up to 70 per cent of metals previously found in car catalysts currently end up on the roadside.