(AP) — Nearly a mile underground in an abandoned gold mine, one of the most important quests in physics has come up empty-handed.

Scientists announced Wednesday that the most advanced Earth-based search for dark matter turned up absolutely no evidence of the mysterious material that has mass but cannot be seen.

Physicists released the initial findings after the first few months of experiments at the Sanford Underground Research Facility, which was built in the former Homestake gold mine in South Dakota’s Black Hills.

The site’s underground location helps screen out background radiation, potentially making it easier for scientists to trap dark matter, which they hoped would be revealed in the form of weakly interacting particles nicknamed WIMPS.