One of the country’s biggest street cleaning firms has announced it is to “mine” the sweepings it collects from roads and pavements, in search of gold and other precious metals.

Veolia Environmental Services believes it can find at least £1 million worth of materials like platinum, palladium and rhodium from the muck swept up from Britain’s streets each year.

Strange as it may seem this story is in fact true. The catalytic converters that we all have on our cars and trucks do indeed degrade over time. And the platinum group metals (pgms) that they are made from do indeed end up in the dust on the side of the road.

It’s not worth your going out and sweeping up some of that dust in order to get rich: we’re talking about levels of the three metals in the 400 parts per billion range. Or 0.4 of a gramme per tonne of material: and that’s the very fine dust too, not everything that gets swept up off the street. It is, probably, worth those who are already sweeping it up trying to treat this to extract those metals. A very rough back of the envelope calculation gives me a value of metals contained of about £200 per tonne of this very fine dust.

Although they won’t in fact do that: they’ll try to treat it only to the level where the normal recycling system will take it as something worth processing for those metals values.

There really is gold in them thar streets: just not very much of it.