COLOMAC GOLD PROJECT

Colomac lies within the north central portion of Nighthawk’s Indin Lake Gold Property.  The regional land package consists of a contiguous position surrounding the Colomac gold deposit, and includes more than 90% of the Indin Lake Greenstone Belt. Access to the project area is by winter road from Yellowknife or year-round by chartered aircraft making use of Colomac’s 5,000 foot airstrip.

Colomac was acquired in late 2011, and in 2012 the Company conducted 11,235 metres of drilling as well as relogging and resampling of the historic core (approximately 85,178 metres of historical drilling) in order to prepare a NI 43-101 compliant technical report outlining 2.1 million ounces of inferred mineral resources. Between 2013 and 2017, the Company was able to add an additional 44,600 metres of drilling, and produced an updated resource estimate as at June 13, 2018 outlining 50.3 Mt at an average grade of 1.62 g/t Au for 2.6 Mozs of inferred resources(see Resources).

The main focus for exploration has been the continued delineation of the sill material (Colomac Main Sill and Goldcrest Sill), where most of the drilling to date has been concentrated on the Colomac Main Sill. In 2014, a high-grade discovery was made within the Colomac Main Sill, and has remained the immediate focus for Company, presenting a new opportunity for the project.

Moving forward, drilling at Colomac will focus on further delineation of high grade zones, namely 1.5 and 3.5, and possibly 1.0, as well as infill drilling within the current resource. Expanded metallurgical testing with sampling of additional zones along the Colomac and Goldcrest sills. The program will also involve a greater number of tests to continue evaluating the deposit’s heap leach potential.

2.6 Moz. Inferred Resource (50.3 Mt at 1.642 g/t Au)

  • 5 deposits (Colomac, Goldcrest, Grizzly Bear, 24 & 27)

  • Wide zones of near surface mineralization

  • No royalties

Considerable Growth Potential

  • ~16 km long underexplored host rock

  • Potential for multi-million ounce resource

  • Newly discovered high-grade gold zone

  • Newly discovered Nice Lake sill yet to be drilled

Excellent Preliminary Metallurgy

  • High recoveries of 96.5% to 98.0%3

  • Amenable to standard gold recovery techniques

  • No adverse materials detected

  • Potential for cyanide heap leach option (34.3% up to 82%)

Five separate gold deposits make up the Colomac Project (Colomac Main, Goldcrest North, Goldcrest South, Grizzly Bear, and 24/27), but only Colomac, Goldcrest and more recently Grizzly Bear have been drilled by the Company to date. All deposits remain underexplored and open in all dimensions.  The Colomac Main Deposit was intermittently mined from 1990 to 1997 with reported production of 527,908 ounces of gold with an average head grade of 1.66 grams per tonne gold.   The other deposits remain untouched, thus mining activities have only impacted a small portion of the sill’s 7 kilometre mineralized strike length.  All mining and processing equipment and infrastructure have been removed from the property.

COLOMAC GEOLOGY & MINERALIZATION


The Colomac Project is contained within the Indin Lake Greenstone Belt, an Archean-aged volcanic arc similar in character to the prolific Abitibi Greenstone Belt of Canada and the Kalgoorlie Greenstone Belt of Australia. The Indin Lake belt formed in an ancient sea with two main periods dominated by volcanic activity, followed by a quiet period during which sedimentary rocks were deposited on top. Volcanoes associated with the first two periods were fed by an underlying magmatic system(s), from which magma intruded into the overlying stratigraphy during the second period and formed horizontal sills such as at Colomac and Goldcrest.

Throughout time, the belt has been deformed (i.e. folded and faulted) multiple times and the majority of the belt has been metamorphosed up to greenschist facies. These two factors are vital to the source, transportation, and concentration of gold and are shared by all prospective greenstone belts. Deformation also resulted in the rotation of the entire stratigraphy such that the top of the units now face to the east and horizontal units are now vertical.

Many styles of mineralization utilize a variety of favourable geologic sites within the belt. At Colomac and Goldcrest, gold is hosted within a differentiated mafic sill. Sills are one component of the magmatic system that would have fed the overlying volcanic pile as the greenstone belt was forming. In the example at Colomac, the magma separated (i.e. differentiated) into an iron/magnesium-rich base and a silica/sodic-rich top. As a result, the bottom of the sill has a strong magnetic signature that is easily identified in airborne surveys, and the top is extremely brittle relative to the surrounding volcanic units. As the belt underwent deformation, the top of the sill cracked while the softer surrounding rocks flowed like plastic. Extensive cracking in the upper part of the sill created a network of pathways that focused gold-bearing fluids thereby concentrating the yellow metal.

By comparison, the nearby Grizzly Bear and the 24/27 Zones formed in a completely different geologic setting. Here, gold fluids utilized a structure occurring at the contact between volcanic and sedimentary rocks, two units with very different characteristics. During deformation, the contrasts between these units allowed for spaces to form that provided pathways and traps for gold-bearing fluids. Volcanic-sedimentary contacts are important geological settings in the Indin Lake Belt as this setting is associated with deposits at the Leta Arm and Treasure Island.

Historically, the Indin Lake Belt has been underexplored; therefore many questions remain about the controlling factors on gold mineralization. Unlike the Abitibi gold camp, the Indin Lake belt has not been the subject of nearly as much study, mining, and exploration in the past. With 90% of the greenstone belt controlled by Nighthawk, the undiscovered potential of the Indin Lake belt is considered highly prospective by the Company’s exploration team. Using their depth of experience, the team continues to unlock new insights into gold mineralization at Colomac and the Indin LakeGold Property as a whole as they continue to develop Canada’s next gold camp.

BRIEF HISTORY OF COLOMAC

 

  • 1945 - Colomac Property discovered
  • 1990 - Neptune Resources completes mill in March; first gold pour in May
  • 1990 - Exploration expenditures to production: C$20 million
  • 1990 - Capital required to production: C$200 million
  • 1991 - Mine closed due to mechanical problems and low gold prices
     
  • 1994 - Royal Oak purchases and recommences production;  mine employed approximately 250 workers
  • 1997 - Colomac closed in August 1997 due to low gold prices
  • 1998-1999 – Royal Oak goes into receivership
  • 2000-2011 – Colomac Property goes to Department of Indian Affairs & Northern Development (DIAND); goes through reclamation process
  • 2012 – Nighthawk acquires mineral claims and leases of the former producing Colomac Mine
HISTORIC GOLD PRODUCTION FROM MAIN ZONE AT COLOMAC

 

Year

Ounces
Produced

Tonnes
Milled

Head Grade
(g/tonne)

Recovery

Cash Cost/oz
(US$)

Average
Gold Price
(US$)

1990

64,500

1,040,000

1.89

90%

300

384

1991

74,100

1,131,000

2.19

94%

NA

362

1994

40,568

985,091

1.58

87%

NA

384

1995

117,646

2,725,388

1.61

92%

383

384

1996

122,416

3,013,156

1.58

87%

370

388

1997

108,678

2,906,081

1.51

85%

354

331

Total:

527,908

11,800,716

1.66

89%

 

 


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Oct 22, 2018

46.25 Metres of 3.31 gpt Au, Including 21.75 Metres of 6.23 gpt Au, and 7.75 Metres of 14.20 gpt Au; and 18.50 Metres of 7.37 gpt Au, Including 8.00 Metres of 16.14 gpt Au, and 5.25 Metres of...

Sep 18, 2018

Nighthawk Gold Corp. ("Nighthawk" or the "Company") (TSX: NHK; OTCQX: MIMZF) is pleased to report drill results for eighteen holes (5,508 metres) recently completed at high-grade Zone 1.5, part of...

Sep 11, 2018

Nighthawk Gold Corp. ("Nighthawk" or the "Company") (TSX: NHK; OTCQX: MIMZF) is pleased to report drill results from seven holes (2,325 metres) recently completed within high-grade Zone 3.5, part...

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