It’s used as cheap gravel on roads, but the unassuming rock olivine could also clean up factories and suck a greenhouse gas from the air.

Olivine is found across the South Island and contains iron, silicon and magnesium – all sought-after materials. Typically, vast amounts of planet-heating carbon emissions are produced mining and refining these minerals around the globe.

Now, Christchurch scientists Chris Oze and Megan Danczyk have a carbon-free way to pull them from olivine. The pair needs $10 million to build their first plant before their idea could “reverse” climate change, says Chris.

Pepsi could be an early customer. Chris and Megan’s start-up company Aspiring Materials is part of its greenhouse accelerator scheme. The food and beverage giant’s New Zealand facility could receive the team’s initial load of carbon-capturing material.

But first, Chris and Megan will need to take the process from the lab to small-scale production. From next year, the proposed $10m pilot plant could transform one tonne of olivine per day into refined minerals – saving up to three tonnes of carbon pollution.

Olivine – “the most abundant rock on Earth” – is combined with acidic liquid, and transformed into an elemental soup using renewable electricity, Megan says. The iron, silica and magnesium are separated and can be sold – replacing other mining operations.

“People are making this stuff already… We’re just making them without carbon,” she says.

Silica would reduce the carbon footprint of concrete. Typically, cement factories emit lots of carbon dioxide when they transform limestone into lime – but the team’s silica can replace up to 30 per cent of the lime required.

“Cement’s one of the largest carbon dioxide emitters, globally,” says Megan.

The iron could go to steel-making factories, again helping to reduce the impact of these high-emitting facilities.

But the magnesium has got the project the most attention – even catching the eye of the X Prize, a global climate tech competition sponsored by Tesla and SpaceX chief executive Elon Musk. Fellow billionaire Bill Gates is also supporting Aspiring Materials through his green tech programme.

The start-up transforms olivine – the most abundant type of rock on Earth, according to the scientists. Photo: Aspiring Materials/Supplied.

In wet conditions, the magnesium in olivine absorbs carbon dioxide – doing it on hills and mountains just as it does in the lab, says Chris. But in the natural world, it can take decades or centuries for the rock to absorb significant amounts of planet-heating gas.

By purifying the mineral, the absorption is turbocharged, he says.

“People are trying to condense carbon dioxide to have it react with the rock. We’ve done the exact opposite… we’re freeing up the magnesium to do its job naturally. It wants to react with the carbon dioxide.”

A carbon-capture device could vacuum up emissions from a high-polluting factory before they leave the smokestack, or be used to bring down the amount of greenhouse gas in the atmosphere.

The final product, magnesium carbonate – a “totally stable”, fire-retardant substance – could be used in the construction industry, Megan says, for example to make drywall.

As the magnesium meets carbon dioxide, it forms a solid substance that could be used in construction. Photo: Aspiring Materials/Supplied.

The team wants a zero-waste process. After the iron, silica and magnesium is removed, a “salty solution” remains, says Chris. That liquid can be split using electricity to make oxygen and hydrogen gas – two more desirable products.

“Everything gets recycled.”

Putting everything to good use also makes the process cost-effective, he says.

“If we sold all the other products – the hydrogen, the iron, the silica – … we can offer direct-air or industry carbon capture for free.”

Chris and Megan, who both shifted from the US to New Zealand to develop this technology, find optimism in their work’s ability to save emissions and the planet.

“The future is going to be amazing. We can’t lose sight of that,' says Chris.

Olivia Wannan/Stuff.