Location and Land
The Mirado gold project is located 35 km southeast of the gold mining Town of Kirkland Lake in northeastern Ontario. The entire Mirado property encompasses 5,800 acres. The focus of the Mirado Gold Project consists of 12 contiguous patented claims, with surface and mining rights, owned 100% by Orefinders.
Surrounding the core patented claims, Orefinders has optioned and/or staked 37 additional contiguous claims covering approximately 10 km of prospective strike length. This includes Orefinders 100% owned MZ property which forms the western extension of the Mirado Mine's in pit resource.
The Mirado gold project is situated within the Abitibi Gold District which has historically produced more than 200 million ounces of gold over the past century, with more than 100 million ounces of gold in current reserves. The prolific Kirkland Lake mining camp is located in eastern Ontario close to the Quebec border and has historically produced 50 million ounces of gold. Much of the historical Kirkland Lake gold production has taken place along or near a major regional geological fault structure known as the Larder Lake-Cadillac Fault (LLCF).
A regional geological map indicates the location of the Mirado property in relation to all of the major gold deposits located along or near the LLCF. Mirado property is favorably located near the top of an Achaean intermediate to felsic, fragmental calc-alkaline volcanic sequence known as the Skead Assemblage. Gold mineralization is structurally controlled and has been identified along NW-SE trending shear zones. North-South brittle structures have also been recognized on the property as being favourable for gold mineralization. A regional northwest trending fault defines the upper contact of the Skead Assemblage with ultramafic to mafic metavolcanic rocks of the McElroy Assemblage. This faulted contact is situated on the northern half of the property.
Gold on the Mirado Gold Property was first discovered in the early 1920's and later mined by underground methods to a depth of 500' in the 1940's. Since then several exploration programs, diamond drilling campaigns, and underground and open pit mining activities have taken place. Over 40,000m of drilling completed by several companies including Mirado Nickel Mines, Broulan Reef, Amax Minerals Exploration, and Golden Shield Resources Inc (Golden Shield). The previous work can be reviewed in historic reports available on the Ontario government website, which includes an environmental base line study, bulk sampling, stockpiling of open pit and underground material and metallurgical test-work programs. Dynatec Mining Ltd. was contracted by Golden Shield in 1986 for underground and open pit operations. Much of the Mirado south zone was pre-stripped and an open pit was mined to a depth of 30m. The material removed from the pit was stockpiles on the Mirado property where is remains today.
Metallurgical test-work was undertaken under the supervision of A. S. Hayden of EH Associates in 1986. Settling and filtration tests were conducted and test slurries were prepared by Lakefield Research. A study of three alternative metallurgical processes was undertaken, including (1) selective flotation with cyanidation of concentrate; (2) direct cyanidation of ore with Merrill- Crowe recovery; and (3) direct cyanidation of ore, with carbon in pulp gold recovery. Gold recoveries up to 95% were realized. In addition to amalgamation and flotation test-work metallurgical recovery studies, ore microscopy and mineralogical studies were completed, and the Bond Work Index was determined to be favorable due to the general lack of quartz veins in the Mirado gold mineralization.
In the second half of 2016 Orefinders completed its Stockpile Project which included crushing, shipping and milling of the resource that was blasted and mined from the Mirado open pit mine during its production in the 1980's. Orefinders completed a resource calculation on the Stockpiles which delineated an inferred resource of 20,742 tonnes at an average grade of 4.41 grams per tonne for a total of 2,939 contained gold ounces as disclosed in the Technical Report filed on Sedar on December 13, 2013.
The Stockpile Project was milled at IAMGOLD's Westwood Mine in Quebec.
In June 2013 Orefinders commissioned a mineral resource estimate for the Mirado project which includes existing historical stockpiles. The mineral resource estimate based on the 2013 drilling program has now been finalized. The mineral resource estimate combines 12,049 m (40 holes) of diamond drilling completed in 2013 by Orefinders and 19,597 m of diamond drilling completed by previous operators during the 1980's.
In addition, approximately 2.2km2 of prospective ground has been covered by ground geophysics, including deep penetrating chargeability and resistivity IP and magnetics.
The report considers the gold mineralization at the Mirado project as primarily amenable to open pit extraction. Open pit resources are reported at a cut-off grade of 0.45 gpt gold within a conceptual pit shell. The mineral resources have been estimated using a geostatistical block modelling approach informed from core borehole data. Gold mineralized zones were defined using a wireframe interpretation constructed from drilling data using Leapfrog(r) and GEMS software. Orefinders drilling efforts focused primarily on the Main zone; however, the North block and down dip extensions to the known mineralization were also tested to a limited extent. In order to determine the quantities of material offering "reasonable prospects for economic extraction" using an open pit scenario, a conceptual pit shell was developed using Whittle software and its Lerchs-Grossman optimization algorithm. The optimization parameters used by SRK are presented in Table 1.
Table 1: Conceptual Assumptions Considered for Open Pit Resource Reporting
|Pit wall angle
|Mining cost (ore and waste)
|Process cost including G & A costs
|Assumed process rate
||5,000 tpd from open pit and underground
||US$1,400 /oz gold
|Mining dilution and losses
SRK advised that a reporting cut-off grade of 0.45 gpt gold is appropriate for reporting open pit and stockpile mineral resources considering a gold price of US$1,400 per ounce of gold and a gold recovery of 95 percent. SRK considers that a cut-off grade of 2.0 gpt gold is appropriate for reporting underground mineral resources.
However, Orefinders elected to report the stockpile mineral resources at a cut-off grade of 2.0 gpt gold in the view of possible off-site toll milling prior to any mine development. SRK considers this cut-off grade to be reasonable.
The Mineral Resource Statement for the open pit, underground and three stockpiles is presented in Table 2.
Table 2: Mineral Resource Statement*, Mirado Gold Project, Ontario, SRK Consulting (Canada) Inc., November 18, 2013
|Classification / Zone
||Gold (000 ounces)
* Mineral resources are not mineral reserves and do not have a demonstrated economic viability. All figures have been rounded to reflect the relative accuracy of the estimates. Reported at a cut-off grade of 0.45 gpt gold for resources inside a conceptual pit; and 2.0 gpt gold for mineralized piles and for resources for which an underground extraction scenario is assumed; a gold price of US$1,400 per ounce; and metallurgical recovery of 95 percent.
** Mineral resources in historical mineralized piles have been reported by Orefinders in a news release dated October 30, 2013.
The full NI 43-101 Technical Report is now available on SEDAR.
An Environmental Baseline Study (EBS) is currently underway (see news release dated September 17th, 2013), under the management of Story Environmental Inc. Surface and ground water testing/monitoring and benthic sampling has begun on the property. A weather station has also been installed on site as well as an air quality monitoring station.
First Nations communication is important to Orefinders with regard to the future development of the Mirado Property.