Excavation of the enormous hoard of Celtic coins discovered by metal detectorists on the Channel Island of Jersey in 2012 is finally complete. Comprised of almost 70,000 coins, multiple gold torcs, glass beads and organic materials including plant fibers, a leather bag and a bag woven with silver and gold thread, the Le Catillon II treasure is the largest Celtic coin hoard ever discovered, six times larger than the runner-up.

When Reg Mead and Richard Miles found the hoard after 30 years of searching the same field because of a story they’d heard from the previous landowners daughter, they only dug down to the surface of the mass of coins before alerting Jersey Heritage so the professionals could take over the excavation. With such a great quantity of coins corroded together, archaeologists dug the entire hoard out of the ground in a single soil block measuring 4.5 x 2.6 feet and weighing three quarters of a ton.

The block was transported to the Jersey Museum where it was painstakingly excavated in the glass-walled laboratory in full public view. The museum’s conservator Neil Mahrer worked with a team of experts and volunteers to document, recover, identify and clean every single speck of archaeological material. For the first two years, they focused on removing and cleaning 2,000 loose coins on the surface of the block. In 2014 excavation of the coin mass began. The overwhelming majority of the coins were found to date to 30-50 B.C. and were made by the Coriosolite tribe of what is now Brittany.

Here’s a timelapse video showing the recovery of objects from the block during just one week, November 21-27, 2015.

Before a coin was removed from the block it was laser scanned so its exact position was recorded, and then once it was removed it was laser scanned on its own. One small subblock of coins was not excavated. Instead, it was snugly plastic wrapped and removed whole so that future conservators armed with new technologies have a clean, original section to study.

The scanning and removal of all the rest of the hoard took a lot of time. Four years after the find and almost three years after the excavation of the soil block began, Neil Mahrer scanned and removed the last ten coins of 70,000. Because the Jersey Museum team is composed of wise and provident people with a care for our nerdly needs, they had it filmed.

Neil Mahrer, who has led the conservation project from the beginning, said: “This is a significant milestone for the team. It has been painstaking but thoroughly intriguing work, which has delivered some very unexpected and amazing finds along the way.

“There is still plenty to do and I am sure the hoard will continue to surprise us as we clean and record the material.”