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Rattlesnake Hills Gold Project


The Rattlesnake Hills Gold Project is located in Central Wyoming approximately 100 kilometres southwest of Casper on the western side of Natrona County. The Rattlesnake Hills Gold Project encompasses the Rattlesnake Hills Gold District nearly in its entirety and is a district scale gold exploration project comprising of 1,573 unpatented lode mining claims as well as 8 Wyoming State mining leases covering an area of approximately 30,400 acres. 

Within the Rattlesnake Hills Gold Project, four significant zones of alteration and precious metal (gold and silver) mineralization have been identified that are associated with Eocene age alkalic intrusions at North Stock, Antelope Basin, South Stock and Blackjack. All four zones have been drilled and broad zones of low grade gold mineralization, as well as narrow discrete zones of high grade gold mineralization have been intersected, as indicated by the following highlights:

Prospect Drillhole From (m) To (m) Interval (m) Au (g/t) Ag (g/t)
North Stock RSC-089 228.60 230.13 1.52 82.90 33.90
North Stock RSC-007 108.21 344.43 236.22 1.86 2.65
Antelope Basin RSC-153 91.44 193.55 102.11 1.72 1.54
South Stock RSC-180 199.65 202.69 3.05 9.30 6.50
Blackjack NVJ-001 0.00 33.53 33.53 1.33 19.56

The Rattlesnake Hills Gold Project is centrally located within a roughly 1,500-kilometre-long belt of alkalic intrusive complexes that occur along the eastern side of the Rocky Mountains from Montana to New Mexico, several of which are associated with multiple +1-million-ounce gold deposits.

Comparing similar deposit characteristics,
Cripple Creek (Newmont), to Rattlesnake Hills Gold Project

Characteristic Cripple Creek Rattlesnake Hills Gold
Qtz poor alt/mi

Voluminous K & Carb altn

Minor acid altn



Peripheral propylitic altn

Multiple magmatic events

Multiple hydrothermal events

Lithologic contacts as fluid paths

Te rich minerals


High Au/Ag

High Au/base metals


Within the Rattlesnake Hills Gold Project, four significant zones of alteration and precious metal (gold and silver) mineralization have been identified that are associated with Eocene age alkalic intrusions at North Stock, Antelope Basin, South Stock and Blackjack . All four zones have been drilled and broad zones of low grade gold mineralization, as well as narrow discrete zones of high grade gold mineralization.

North Stock

Precious metal mineralization at the North Stock area has been defined by historic and more recent drilling and is outlined in a broad 100 metre x 300 metre tabular mineralized zone, extending to a depth of about 500 metres. North Stock drilling highlights include intercepts of 1.85 grams of gold per tonne (g/t Au) over 236.16 metres hole length (Hole RSC – 007) and 2.08 g/t Au over 150.88 m hole length (Hole RSC – 039). The system remains open to the north, west and south toward the Antelope Basin target.

Drilling was successful in identifying both narrow high grade as well as broad low grade gold and silver mineralization at depth. Selected highlight drill intersections for North Stock are presented here:

Selected North Stock drill highlights.

Hole From (m) To (m) Length (m)* Au (g/t) Ag (g/t)
RSC-003 205.74 240.79 35.05 4.79 3.29
RSC-007 108.20 344.36 236.16 1.85 2.65
RSC-020 143.26 198.91 55.66 9.73 16.64
Including 160.02 176.78 16.76 26.21 40.39
Including 170.69 172.21 1.52 122.00 122.00
RSC-039 25.91 176.78 150.88 2.08 2.97
Including 103.63 106.68 3.05 12.95 0.00
RSC-089 83.82 213.36 129.54 2.08 6.47
RSC-089 216.41 243.84 27.43 7.85 7.33
RSC-089 278.89 286.51 7.62 10.65 2.76
Including 228.60 230.12 1.52 82.90 33.90
RSC-093 134.11 163.07 28.96 5.21 11.34
RSC-122 155.45 228.60 73.15 1.78 4.45
RSC-123 83.82 163.07 79.25 1.49 6.31
RSC-126 196.60 256.03 59.44 2.58 4.23
RSC-130 170.69 205.74 35.05 3.95 5.69
RSC-132 112.78 329.18 216.41 1.58 3.68
Including 137.16 140.21 3.05 17.96 12.30
RSC-135 83.82 160.02 76.20 4.68 9.28
Including 144.78 147.83 3.05 45.30 34.80
RSC-136 222.50 263.65 41.15 3.10 3.90
RSC-141 30.48 172.21 141.73 1.90 6.46
RSC-144 91.44 147.83 56.39 2.09 9.49
RSC-144 205.74 251.46 45.72 3.23 7.16
RSC-145 137.16 192.02 54.86 3.20 6.91
RSC-145 204.22 281.94 77.72 4.20 3.75
RSC-145 239.27 240.79 1.52 128.00 23.00
Including 143.26 147.83 4.57 15.67 27.87

*Length (m) is core length

Antelope Basin

The Antelope Basin alteration and gold-silver mineralization has been identified to be associated with Eocene age alkalic intrusions that are part of the Rattlesnake Alkali Intrusive complex. Drilling at Antelope Basin demonstrates broad zones of low grade, as well as narrow discrete zones of high grade, gold and silver mineralization. Mineralization at Antelope Basin has been defined by drilling over an area of 200 metres x 350 metres and to a depth of 200 metres. Highlights from Antelope Basin drilling include 1.91 g/t Au over 76.2 metres hole length (Hole RSC-042) and 1.21 g/t Au over 97.5 metres hole length (Hole RSC-019). Additional drilling results from the Antelope Basing deposit are presented in the table below:

Selected Antelope Basin drill highlights.

Hole From (m) To (m) Length (m)* Au (g/t) Ag (g/t)
RSC-001 169.16 182.88 13.72 2.69 0.62
RSC-019 83.82 181.36 97.54 1.21 0.52
Including 167.64 169.16 1.52 9.35 8.00
RSC-042 147.83 224.03 76.20 1.91 0.50
Including 185.93 187.45 1.52 11.80 7.00
RSC-045 12.19 48.77 36.58 1.44 0.00
RSC-047 97.54 170.69 73.15 1.26 0.17
Including 167.64 169.16 1.52 6.71 0.00
RSC-051 243.84 280.42 36.58 1.33 0.21
RSC-078 173.74 251.46 77.72 1.63 1.60
Including 216.41 217.93 1.52 7.48 3.00
RSC-087 166.12 204.22 38.10 1.34 0.48
RSC-099 77.72 143.26 65.53 1.76 0.44
RSC-100 196.60 271.27 74.68 1.21 0.67
Including 245.36 246.89 1.53 6.26 2.00
RSC-153 143.26 160.02 16.76 2.97 1.45
RSC-153 111.25 120.40 9.14 2.28 0.83
RSC-153 164.59 195.07 30.48 2.09 1.05
RSC-155 134.11 187.45 53.34 1.25 0.80
RSC-180 199.64 202.69 3.05 9.30 6.50

*Length (m) is core length


Gold mineralization hosted within quartz veins has recently been discovered at Blackjack. The mineralized quartz veins are hosted within Archean granitic and amphibolite gneisses and includes drill intersections of up to 1.35 g/t Au over 33.0 metres.

The mineralization at Blackjack is likely related to the mineralization at North Stock and Antelope Basin. In principal, gold mineralization at Blackjack is related to alkalic intrusions but its characteristics are more typical of a low sulphidation epithermal deposit type. The majority of the quartz veining occurs within the Archean succession, although limited mineralization has been identified within the Eocene volcaniclastics. The Blackjack mineralization remains open at depth, down-dip and along strike. Soil sampling completed subsequent to the drilling indicates that the mineralized body continues to the northwest and possibly to the northeast.

After significant gold mineralization was intersected in the 2014 at Blackjack , a soil sampling program was carried out in order to guide future drilling. A strong, V – shaped gold-in-soil anomaly with values of up to 0.85 g/t Au is situated directly above the mineralization identified in drilling. Silver results from the soil sampling program were also extremely promising. In addition, several highly anomalous results were returned up to a maximum value of 16.60 ppm silver. The significant silver-in-soil anomaly correlates well with the gold-in-soil anomaly and again indicates a potential to extend the currently identified zone of mineralization at Blackjack. 



The Rattlesnake Hills of Central Wyoming lie along the north-eastern edge of the Granite Mountains located within the Archean Wyoming geological province. The Rattlesnake Hills are the result of erosion of the northwest plunging Rattlesnake anticline.

Upwards of 42 Eocene trachyte, phonolite and quartz monzodiorite stocks, domes, dykes and plugs that have intruded Precambrian greenstone rocks have been mapped throughout the property, which collectively comprise the Rattlesnake Alkaline Intrusive (RAI) complex (Autenrieth, 2012). Cross cutting relationships indicate the quartz monzodiorite was emplaced first and may be genetically related to the latite and latite porphyry supracrustal rocks at North Stock. Volcaniclastic rocks of the Wagon Bed Formation, interpreted to be coeval with the emplacement of the RAI complex, are preserved within the North Stock Structural Basin (Norby, 1995). A series of northeast and northwest trending dykes parallel structure in the North Stock area and sills intrude the Archean stratigraphy throughout the region.

During the Eocene the Archean rocks in the Rattlesnake Hills were intruded by the RAI complex. The RAI covers an area of approximately 125 km2 and is analogous to gold-bearing alkalic systems in Montana (Golden Sunlight), South Dakota (Wharf) and Colorado (Cripple Creek) (Koehler, 2012). The RAI complex intruded along the intersection of three prominent regional structures:

  • North Granite Mountain Fault: east – west trending fault which bounds the Sweetwater Arch to the north;
  • Belle Fourche Lineament: north east trending lineament which links the RAI complex to alkali intrusive complexes in southwestern and northeastern Wyoming (Leucite Hills and Bear Lodge Mountain, respectively);
  • Rattlesnake Hills Anticline.

Hoch and Frost (1993) divided the RAI complex into three groups (the Eastern Felsic Group – EFG, the Western Felsic Group – WFG and the Central Alkaline Group – CAG) based largely on location and lithology. The EFG intrusions are located along the northeast limb of the Rattlesnake anticline and include quartz latites and rhyolites. The WFG, which makes up the southwest portion of the RAI complex, is mineralogically and chemically similar to the EFG, only differing texturally (Koehler, 2012). The WFG straddles the North Granite Mountain fault. The EFG and WFG consist of large, up to 1,800 m in diameter, domes. The bulk of the precious metal mineralization identified to date in the Rattlesnake Hills Gold Project area is hosted within the CAG. The CAG comprises phonolite, trachyte and latite domes of less than 500 m in diameter located proximal to the axis of the Rattlesnake anticline (Pekarek, 1977). The three groups broadly lie along the Belle Fourche Lineament (BFL) which links the RAI complex to other alkalic complexes regionally.

Extensive widespread alteration footprints have been mapped throughout the Rattlesnake Hills Gold Project. In total, ten distinct alteration assemblages, four major and six minor, have been identified. The major alteration types in decreasing order of abundance are: carbonate, potassic, clay and Fe/Mn oxide-hydroxide (FEOH). The minor alteration assemblages include late silica/chalcedony, sericitization, actinolite-riebeckite-magnetite, roscoelite, talc, epidote-hematite and phlogopite. The extensive and complex nature of the hydrothermal alteration mapped throughout the property is indicative of a large prolonged or multiphase Tertiary hydrothermal event affecting the Archean lithologies throughout the project area.


To view a the most recent NI 43-101 Technical Report on the Rattlesnake Hills Gold Project, click here.

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