Mapping a Volcanogenic Massive Sulphide Deposit

Proof-of-concept trial of muon tomography, imaging the Price deposit — a multi-metal volcanogenic massive sulphide (VMS) ore body at Nyrstar’s Myra Falls underground mine.

Myra Falls Mine


British Columbia, Canada




Polymetallic volcanogenic massive sulfide



The Myra Falls underground mine was located under a provincial park in an environmentally sensitive area, and exploration drilling from surface was to be avoided. The Price deposit is a polymetallic volcanogenic massive sulfide (VMS), containing zinc, copper, lead and silver, providing good density contrast from the surrounding rock. The deposit is particularly amenable to imaging with muon tomography because it is located about 70 m below the surface, where muon intensity is quite high.


A single muon detector was placed in a drift below and to the side of the known Price deposit, situated about 300 m below the surface under steep terrain. The detector was positioned for 15–20 days at seven different locations.


The muon tomography results agreed well with measurements from underground drill core data. After a total exposure time of a few months, the radiographs from each detector location were incorporated in a 3D inversion.

“Because this technology has the potential to detect and image deposits at depth, it will refine the exploration search area, which will reduce the amount of expensive drilling required and further efforts to minimize environmental impact.”
Rick Sawyer
Manager, Exploration and Geology