Giving the scanners something to see

Most core sheds already have hyperspectral scanners. They can characterise rock types, but they can't see metal grade because the signal is too faint or often isn't there at all.

Fieldstone's answer is biological. The company engineers microbes that produce a distinct signal when they encounter a specific metal. Applied to a sample, that signal is read by a hyperspectral camera and Fieldstone's software turns it into a low-cost, high-density read of the target elements.

"We read the target elements directly and get that data to the geologist within a day of the sample coming out of the ground," says Fields, "at a cost that makes it practical to test every interval. Denser coverage, earlier, is where the advantage sits."

Fieldstone has sensors for gold, copper, arsenic, and molybdenum in-house, with more in development. It already processes customer samples at its lab in Nevada. Through a DOE ARPA-E award with TerraCore and MIT, it is building the same readout into core scanning at active drill sites.

From pilot to standard workflow

For Fieldstone, the science is no longer the hard part. The challenge now is operational, fitting a new measurement platform into the day-to-day running of a major mining company.

"Our science is validated, and we have federal programs behind it," Brandon says. "What we needed was an operator's view of how a mine actually runs and a network of people who've sold into it. Founders Factory gives us both, plus the first investment from inside mining."

Brandon wanted time with Rio Tinto's technical teams on their home ground, to see how exploration and orebody decisions get made inside a major, and where faster, denser elemental data would change them.

The conversation he most wanted to be part of was about integration without disruption. What does it take for a major to move a new measurement tool from a pilot into its standard exploration workflow? In his words, it comes down to "the validation a geologist needs to see, the data standards it has to meet, and who signs off."

Those are questions a startup can't answer from the outside. What has surprised Brandon most is how far Rio Tinto has opened up. "In a few weeks, we've had conversations with teams we wouldn't otherwise have reached, and those conversations are already shaping where our technology goes next." Some have pointed Fieldstone towards problems beyond its current offering, which Perth gave the team a chance to work through in person.

Being in the room counts for more than the scheduled sessions. For Brandon, the real value lies in the one-off comments that open up much larger discussions on ideas the team had never explored.

It all feeds into Fieldstone's next milestone: simplifying its workflows so analysis can happen at the drill site. That means moving from running samples in its own lab, with its own team, to a system anyone can run wherever the data is needed most.

Now is the time 

Brandon points to three changes. Hyperspectral cameras have gone from specialist equipment to established core-scanning tools, so Fieldstone's readout builds on technology the industry already trusts. Synthetic biology has matured enough to engineer reliable, element-specific sensors.

And demand for critical minerals has turned exploration speed into a strategic issue, especially for countries trying to secure domestic supply.

"Exploration timelines are measured in years," Brandon says, "and lab turnaround is one of the few bottlenecks you can cut from weeks to a day."

Letting customers set the roadmap

The biggest lesson Brandon has learned this year is to let customers set the roadmap. Biology can sense an enormous range of targets, and the temptation is to chase all of them.

"We've moved faster by building what customers need now," he says. That focus took Fieldstone from its first mining samples to processing commercial samples at its own lab in Nevada within a year.

His advice to founders applying to Founders Factory follows a similar logic: know exactly what you need to prove and to whom. "'We want to transform exploration' doesn't help anyone help you," he says. "'We need to show our copper reading matches the lab assay on fresh core, and we need a geologist who'll be blunt about whether it's useful' does."

The programme and the portfolio, he adds, are most valuable when you show up with a specific question. In Perth, Fieldstone brought one, wanting to know how to get from a validated pilot to the standard workflow of a major. They left with the people best placed to answer it.

Fieldstone is part of the fifth Mining Tech cohort delivered by Founders Factory in partnership with the Rio Tinto.