Geological Setting

Stratigraphy of the Belt Supergroup in the Troy area (from Harrison & Cressman, 1983) Click image for larger chart.

The geology of the general area is characterized by a thick sedimentary sequence Proterozoic in age. Within this sequence, there are four major conformable groups: Lower Belt, Ravalli, Middle Belt Carbonate and Missoula Groups. The Troy Mine and Rock Creek project are found within the Ravalli Group and specifically in the Revett Formation.

These formations represent a mature, clastic sandstone of varying thicknesses with the sulphide mineralization being stratabound and disseminated. Copper and silver mineralization occurs throughout the Revett Formation (in excess of 2,000 feet thick).