Gold Rock Project is 100% held by Calibre Mining Corp. through its subsidiary, Calibre Gold Rock LLC.
On February 23, 2025, Equinox Gold agreed to acquire Calibre Mining in an at-market merger, creating a diversified Americas-focused gold producer. The combined company, retaining the Equinox Gold Corp. name, will be 65% owned by Equinox shareholders and 35% by former Calibre shareholders. Approvals are expected by May 31, 2025.
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Summary:
Deposit Types
The Gold Rock Property is a Carlin-type gold deposit (CTGD) and features sediment-hosted, disseminated gold deposited within Mississippian limestone and siltstone units, namely the Joana Limestone and, to a lesser extent, the overlying Chainman Shale and underlying Pilot Shale. CTGDs in northern Nevada are divided into a series of trends. The Gold Rock Property lies on the south eastern end of the Battle Mountain-Eureka Trend. Several authors propose that the trends for CTGDs in northern Nevada reflect structural lineaments in the basement (e.g. Cline et al., 2005; Muntean et al., 2011). The Battle Mountain Eureka trend corresponds to a boundary between two portions of crust which have different Gravity and Magnetic signatures (Grauch et al., 1995, 1998; Tosdal, 1999).
Carlin-type gold deposits in northern Nevada represent the second highest concentration of Au in the world and around 6% of global annual Au production (Muntean et al. 2011).
Geometry of Mineralization
The primary feeder structure at Gold Rock is postulated to be a steeply dipping reverse fault reactivated with extensional dip-slip, known as the EZ Junior Fault (Carden, 1988). The EZ Junior Fault is adjacent to and sub-parallel with the western limb of the EZ Junior Anticline in the area of the EZ Junior open pit. When these fluids intercepted rock with the favorable geochemistry and porosity (Joana Limestone and Chainman Shale), the fluids reacted with the rocks causing first the formation of solution breccias and then more violent hydrothermal breccias as the reactions progressed. Gold would have precipitated as part of this fluid-rock reaction. It is likely that the complex faulting and folding on the property provided fluid pathways and traps which accentuated the mineralization in specific areas.
The geology of the Gold Rock Property is dominated by Devonian through Mississippian limestone, shale, and sandstone. These rock types are exposed in a series of north-trending ridges that represent stacked, easterly-directed thrust blocks and low amplitude, open to tight folds. Gold mineralization is interpreted to postdate thrusting and folding. Mineralization at Gold Rock is localized in the apex and limbs of the slightly overturned, fault-bounded, EZ Junior Anticline. The primary host is the Joana Limestone, but mineralization is also hosted in the overlying Chainman Formation in calcareous shale and carbonate units. Scattered, minor, inconsistent mineralization also occurs in the underlying Pilot Formation. Gold mineralization was exposed at the pre-mining surface of the historical EZ Junior open pit. Along strike, the mineralized lower Chainman Formation and upper Joana Limestone are covered by 300 to 500 ft (90 to 150 m) of poorly exposed Chainman Shale. Mining at the EZ Junior open pit extracted a small portion of the near surface resource. Historical drill intercepts indicate that significant mineralization still exists below the EZ Junior open pit and along strike to the north and south.
At the apex of the EZ Junior Anticline, the mineralization is largely restricted to Joana Limestone and the base of the overlying Chainman Shale. In both the east and west limbs, mineralization extends downward, largely in the Joana Limestone.
Mineralization was exposed at the pre-mining surface of the EZ Junior open pit. Along strike (6,000 ft [1,830 m] south-southwest and 1,000 ft [305 m] north-northeast of the EZ Junior Pit), the mineralized lower Chainman Shale and upper Joana Limestone are covered by 300 to 500 ft (90 to 150 m) of poorly exposed Chainman Shale. Mining at EZ Junior extracted a small portion of the near surface resource. Historical drill intercepts indicate that significant mineralization still exists below the EZ Junior open pit and along strike to the north and south.
Additionally, historical drilling at Meridian Flats, nearly a mile south of the EZ Junior open pit, intersected significant mineralization within the same faulted anticline geometry. In general, the trace of the EZ Junior Anticline hinge zone is fairly horizontal and oriented at about N14oE along the length of the Gold Rock resource area. Locally, the EZ Junior Anticline can display slight plunges in and around cross faults. However, the depth from surface to the top of the EZ Junior Anticline appears to be more affected by elevation changes on either side of the cross faults due to some vertical movement along the faults than by plunge of the anticline. This also likely can be said for the main trend of the known EZ Junior mineralization as it appears to be spatially related to the anticline hinge zone and the contact between the Joana and the Chainman formations.