The Rimrock property is a Midas-style gold-silver property situated in the Midas (“Northern Nevada Rifts”) gold trend and also directly along a domed up portion of the Carlin Gold Trend, 8 Km northwest of Waterton Global’s Hollister gold-silver mine, and 16 Km east southeast of Newmont’s Midas Mine property. The Rimrock property comprises 54 lode claims that cover approximately 1,080 acres. The Hollister Mine has reserves of more than 1,000,000 ounces of high grade gold grading in excess of 1 ounces per ton gold. The Midas Mine had initial mineable reserves of more than 3M oz. of high-grade gold and 25M oz. of silver. The Rimrock property has three old mercury mines in the area, with one situated directly on top of the main gold ore target, which lies at a major fault intersection. The Paleozoic rocks at Rimrock have been domally uplifted to be present at surface, immediately west of the property boundary. Consequently, the rocks with Carlin-style gold potential could be much closer to the surface than at Hollister or at Midas. Anomalously elevated Carlin-only trace element thallium was found in three samples at Rimrock. This represents a geochemical leakage-upward anomaly of thallium and arsenic. The Company is now focused upon the discovery of relatively shallower Midas style gold-silver deposits.
In April 2013, announce that it has completed an initial geological mapping and geochemical sampling program on the Rimrock gold-silver property in Elko County, Nevada. The new geologic mapping has shown that the Rimrock gold property contains a large-scale, multiple-fault dilation zone gold-silver target situated just north of the Hollister Mine.
The principal epithermal Midas style gold-silver target was validated and even augmented by the new geologic mapping and sampling. Seventeen new samples were taken and analyzed, to further investigate alteration and mineralization seen on the property. These new detailed sample data show anomalous gold (to 13 ppb Au), silver (to 0.87 ppm Ag), antimony (to 5.5 ppm Sb), arsenic (to 39.5 ppm As), mercury (to 327 ppm Hg), selenium (to 6.5 ppm Se), and thallium (to 3.45 ppm Tl), which could be associated with Midas and Carlin-style gold-silver deposits along certain major fault structures on the property. These were surface spot rock chip samples taken well above the zone where anomalous gold values would be expected to occur. More detailed geochemical data from this program may be found in Rimrock Gold’s upcoming 10Q report.
The “Dilation” target was formulated based upon new geologic mapping and geochemical sampling by Rimrock’s chief consulting geologist. The “Dilation” was formed when the northeast-trending IC Fault “jogged” to the east, forming a dilated rhomboidal shaped block in the jog area, which allowed hydrothermal fluids to more easily migrate upward and cause mercury-arsenic mineralization and alteration at the ground surface. Two small-scale mercury mines are situated in the southwestern part of this “Dilation” fault intersection block at Rimrock. The Dilation target at Rimrock shows highly altered, faulted, silicified felsic tuffaceous volcanic rocks at the surface, overlain by post-mineral rhyolitic flow domes similar to those near the Hollister Mine. The altered rocks locally show significant amounts of opaline silica and local mercury minerals, and local veining that crosscuts these rocks.
Newmont drilled several very shallow rotary drillholes in the project area in 1984 searching for near-surface disseminated gold mineralization. The “top elevations” of epithermal Midas-Hollister type gold-silver targets at Rimrock likely start at 150 to 300 metre depths below surface. The main zone of ore grade gold-silver mineralization at Midas is at least 500 metres in height, below the “top elevations”. Local small poddy bodies of mineralization may occur above this “top elevation” level as at Midas. Rimrock Gold’s exploration efforts are focused upon discovery of deeper Midas and Hollister Mine style gold-silver mineralization, 125 to 300 metres below the surface. The elevations of ore zones at Hollister will be used to help guide exploration on the Rimrock property.
In April 2013, the Company also announced that its contractor Zonge Engineering has completed a new Controlled Source Audio Magnetotelluric (“CSAMT”) geophysical resistivity survey on the Company’s Rimrock gold-silver project. CSAMT surveys have previously been very successful in delineating lithological boundaries and major fault zones in the region, including at the Hollister mine.
Zonge Engineering completed a 4-line survey covering 10.9 line Km east-west across the project property, spaced 250 to 400 meters apart, encompassing numerous geological targets previously identified by the Company’s technical team. The Company is presently interpreting the data with the help of Wright Geophysics. The final interpretations will be used to help select new exploration drilling targets at Rimrock.
Preliminary analysis of the raw CSAMT data appears to provide an excellent basis for defining and interpreting potentially mineralized structures at Rimrock. Some of these structural zones appear to be much wider than previously thought, including the previously identified “Dilation” Midas-style gold-silver target. The CSAMT survey also appears to have better defined the lithological boundary between the older Paleozoic basement rocks and the overlying volcanic rocks present at the surface, along with the geometry of faulting in the property area.
The Paleozoic rocks at Rimrock have been domally uplifted to the surface, immediately west of the property boundary, with Vinini Formation sedimentary rocks present. As a result, the mineralized layer with Carlin-style gold potential could be much closer to the surface than at Hollister or at Midas. Fault feeders for gold are critical in defining where both Midas- and Carlin-style gold mineralized bodies lie, and CSAMT has been proven as an excellent, cost-effective technique to identify fault feeders in the region. An updated evaluation of the northwest extension of the Carlin trend has just been completed, and the Rimrock property is interpreted to lie directly in the heart of this projection of the prolific gold-bearing trend.
In May 2013, the Company announced that its geophysics consultant Wright Geophysics has provided the Company with an initial interpretation of the recently completed Controlled Source Audio Magnetotelluric (“CSAMT”) geophysical resistivity survey on the Company’s wholly-owned Rimrock gold-silver property in Elko County, Nevada. The Rimrock property is strategically located in a highly mineralized epithermal gold-silver district, 7 Km northwest of Rodeo Creek’s Hollister mine, and 16 Km southeast of Newmont’s Midas mine.
The survey covered 10.9 line Km east-west across the property, with four survey lines spaced 250 to 400 meters apart, encompassing all of the previously identified mineralization targets on the property. The CSAMT data were acquired using a 50 meter electric-field receiver dipole, and one CSAMT transmitter, of a grounded dipole configuration. Initial interpretations of the CSAMT survey validate the mineralization model developed by the Company’s technical team, and include the following observations:
- The previously identified “Dilation” gold-silver target on surface along the major “IC Fault Zone” has been verified at depth by the survey.
- The siliceous mineralization associated with the “Dilation” target has been interpreted to be constrained by steeply dipping near-vertical fault zones.
- These fault zones are interpreted to be up to 150 meters in width, representing one of the widest gold-silver targets in the entire Midas-Hollister region, potentially hosting near-surface bulk-mineable gold mineralization.
- The location of older Paleozoic basement rocks has been identified to be between 275 and 375 meters below surface, confirming the mineralization model developed by Company geologists.
The Paleozoic basement is likely part of the siliceous “Upper Plate” Vinini Formation package that lies beneath surface volcanic rocks, and above the Roberts Mountain Thrust fault package that separates the Vinini from “Lower Plate” sedimentary rocks. This “Lower Plate” sedimentary unit is known to host the large Carlin-style gold deposits situated further south at the Goldstrike-BlueStar-Carlin mine complex. The Paleozoic rocks at Rimrock are believed to have been domally uplifted to the surface, immediately west of the property boundary. As a result, the mineralized layer with Carlin-style gold potential could be much closer to the surface at Rimrock than at Hollister or at Midas. An updated evaluation of the northwest extension of the Carlin trend has been recently completed, and the Rimrock project is interpreted to lie directly in the heart of this projection of the prolific gold-bearing trend.
Overall, the new CSAMT data appear to provide a much clearer basis for defining the presence, geometry, and depth extensions of the northerly-trending structures at Rimrock that contain opalite-cinnabar (mercury sulfide) mineralization. The Company is continuing to further interpret the survey data, with the help of Wright Geophysics. The final interpretations will be used to design new exploration drillholes at Rimrock.
In July 2013, the Company announced that it has identified and selected five new drill sites for drilling. The new drill sites were defined through interpretation of geological, geochemical, and geophysical data collected on the project by various former property owners and option-holders over the past 35 years. The Company’s management team has identified several mineralization targets along the IC Fault system, including the large Dilation Zone located between two well-defined faults representing a 100 meter wide drill target area. The Company plans to drill-test the area of convergence of these two faults at the northern and southern ends of the Dilation Zone. The Rimrock project has never been drill-tested specifically for the Midas-style gold-silver mineralization envisioned by the Company’s management. Rock samples from a recently completed surface sampling program at the project show anomalous values of several indicator metals typically associated with Midas-Hollister gold deposits, including arsenic and selenium.
In conclusion the Company’s comprehensive database for the Rimrock project provides a much clearer basis for defining the presence, geometry, and depth extensions of north-south trending structures that contain opalite-cinnabar (mercury sulfide) mineralization. The Company is planning to drill these initial targets, upon posting the requisite reclamation bond and receiving the drill-permit from the U.S. Bureau of Land Management.
These gold-silver targets at the Rimrock property have never been drill tested at depth for Midas-Hollister style gold-silver mineralization, nor for Carlin-style gold mineralization. The Company expects that the Rimrock property offers potential to hold a large, high-grade, underground mineable Midas-Hollister-type Low Sulfidation gold-silver deposit.