Blockchain enthusiasts often stress how the concept isn’t just about cryptocurrencies and a planned program in Africa could prove that point. The idea is to use a blockchain to boost the fight against child labor in cobalt mining.

Cobalt is a key material in producing the lithium ion batteries that make pocket-sized cellphones practical. More than half of the known cobalt still in the ground is in the Democratic Republic of the Congo and human rights groups have criticized tech firms for not doing enough to show they have checked that their suppliers don’t use child labor in the country.

In principle, the solution could be as simple as keeping a paper trail from a batch of cobalt being mined to it being used to make a phone. In practice that’s tricky not just because the supply chain is often complex with multiple middle-men, but because there’s a major incentive for less reputable suppliers to falsify documents.

The World Economic Forum is now developing prototype programs to use a blockchain, a form of digital ledger that’s designed to be extremely difficult (and ideally impractical) to tamper with without being detected.

The idea would be to track cobalt mined by companies known to have good labor practices. It’s suggested each bag of cobalt could be sealed and digitally tagged before being tracked along the supply route. The tag would include both the weight and a spectrometer measurement of the proportion of pure cobalt in the batch (which is what will eventually be made accessible during smelting.)

Reuters notes that blockchain has been trialled successfully with diamond supplies, but the cobalt supply chain has more than twice as many steps to track.