Astronomers Vera Rubin and Fritz Zwicky noticed back in the last century: galaxies move as if held by invisible mass. Discoveries of Edwin Hubble, the concept of Big Bang and cosmic microwave background confirmed that space is filled with dark matter. Direct particle searches failed, and scientists turned to ancient minerals — natural detectors.

Laurionite is the perfect film. For millions of years it lay in hot brines deep underground, recording each collision with a micro-scratch. The film's purity is critical: unwanted exposure would ruin the shot. Laurionite is surprisingly pure — it has almost no radioactive impurities. Its sensitive layer is lead nuclei: they catch even such elusive particles as the hypothetical higgsino. Hydrogen and oxygen in the crystals just hold the structure.

Spectroscopy methods and helium ion microscopy develop ancient scratches. Scanning the stone, physicists see tracks left tens of millions of years ago. Higgsino, invisible to conventional instruments, can leave a mark precisely in a lead target.