The area of the Rainbow occurrence is underlain by strata of the Upper Triassic Stuhini Group intruded by Late Triassic to Early Jurassic quartz monzonitic rock of the Copper Mountain Plutonic Suite. Rock in the Rainbow area is reported to consist of massive light grey limestone, limy sandstone, grits and pebble conglomerate.

The Rainbow mineralization was first discovered by B.C. Geological Survey personnel during a regional mapping program in 2003. Mapping and sampling by Paget Resources in 2005-2006 lead to the discovery of high-grade gold-silver mineralization in the Rainbow basin. Mineralization consists of structurally controlled pyrite-arsenopyrite in brecciated and silicified black chert and thin-bedded silicified limestone.

Structurally controlled brecciation and silicification is associated with these fold/fault structures. White fine­-grained silica healed epithermal breccias and open space lined with drusy quartz are widespread. Gold mineralization has a strong association with zones of fine-grained arsenopyrite, associated with these breccias. Sphalerite, galena and chalcopyrite are also present in minor amounts.

Two holes from the same setup were drilled on the Upper Rainbow target by Paget Resources in 2011 with hole 01 being a failed hole. The target at Upper Rainbow was the chert unit in the hanging wall of the Rainbow fault that was thought to make a good host for an epithermal system. Surface geology reported mineralized, veined and fractured black chert with grab samples up to 59.3 grams per tonne gold (Assessment Report 32564). Hole RN-11-02 did not encounter significant epithermal style mineralization, significant quartz veining, or banded veins. Assay results did not give any significant values for gold or copper mineralization. However, it was noted during core logging that most of the sedimentary bedding structures observed were at low angle to the drill core and it is believed that this hole was drilled down bedding and never encountered the hanging wall of the Rainbow Fault.

See Mary (104G 018) for related details and common work history elements.