Brisco News

Prime Mining Announces Measured and Indicated In-Pit Oxide Mineral Resource of 19.8 Million Tonnes Containing 833,000 Gold Equivalent Ounces at 1.31 gpt at Los Reyes Project, Mexico

By April 2, 2020No Comments

VANCOUVER, British Columbia, April 02, 2020 (GLOBE NEWSWIRE) — Prime Mining Corp. (TSX.V:PRYM) (OTCQB: PRMNF) (Frankfurt:A2PRDW) (“Prime” or the “Company”) is pleased to announce an updated mineral resource estimate (“Updated Resource”) prepared by Stantec Consulting Ltd. (“Stantec”) for Prime’s Los Reyes Oxide Gold and Silver Project located near Cosalá, Mexico (the “Los Reyes”).

The Updated Resource increases total oxide mineralized material and upgrades the assurance category estimate reliability.  The new pit constrained Updated Resource (at 0.22 g/t Au cutoff) increased to 19.8 million tonnes Measured and Indicated plus 7.1 million tonnes Inferred from 6.8 million tonnes Indicated and 3.2 million tonnes Inferred historic global resource (at 0.5 g/t Au cutoff).

The Updated Resource contains 833,082 gold equivalent (“AuEq”) ounces Measured and Indicated at 1.31 g/t and 261,132 AuEq ounces Inferred at 1.14 g/t.

The following is a summary of pit constrained AuEq ounces at various cutoffs:

Table 1: Summary of Pit Constrained Updated Resource in AuEq Ounces

Cutoff Assurance Category Tonnes Average AuEq Contained AuEq
Grade (g/t) Ounces
0.22 g/t cutoff Base Case Measured & Indicated 19,752,000 1.31 833,082
Inferred 7,094,000 1.14 261,132
0.50 g/t cutoff Measured & Indicated 11,822,000 1.85 701,873
Inferred 3,956,000 1.65 209,344
0.70 g/t cutoff Measured & Indicated 8,697,000 2.21 618,123
Inferred 2,603,000 2.09 175,232
0.90 g/t cutoff Measured & Indicated 6,746,000 2.54 550,207
Inferred 1,859,000 2.48 148,160
1.0 g/t cutoff Measured & Indicated 5,914,000 2.72 516,251
Inferred 1,685,000 2.59 140,530

Gold equivalent calculations are based on a gold to silver ratio of 1:83. Pit constrained mineral resources are reported at cut-off grades within conceptual pit shells. The total base case resulting pit strip ratio is 4.6:1 waste to mineralized material. Both gold and silver values are used to determine the value of a given block and the pit shell is defined by: a 0.22 g/t minimum gold cutoff grade, US$2.40 per tonne mining cost, a gold price of US$1,329 per troy ounce and a silver price of US$16 per troy ounce. Mineralization density is based on laboratory analyses on specific lithologies and a default mine rock density is based on 2.6 tonnes/m3 for all other areas. Modifying factors considered for the definition of mineralized zones into classified resources having reasonable prospects for eventual economic extraction are: metallurgical recovery factors of 72% for gold and 25% for silver that are typical for conventional heap leach operations, no allowance for dilution and mining losses in the calculation of the cutoff grade, combined leaching, site costs and overhead of approximately US$4.30 per tonne placed on the leach pad and no refining and royalty costs have been applied.

Table 2: Pit Constrained Updated Resources

Cutoff Assurance Category Tonnes (‘000) Average Au   Contained Au Average Ag Contained Ag Average AuEq Contained AuEq
Grade (g/t)   (oz ‘000) Grade (g/t) (oz ‘000) Grade (g/t) (oz ‘000)
0.22 g/t cutoff total Measured 8,527 1.24 341 28.98 7,946 1.59 436
Indicated 11,225 0.81 293 23.99 8,658 1.10 397
M+I 19,752 1.00   633 26.15 16,604 1.31 833
Inferred 7,094 0.78 179 29.95 6,831 1.14 261
0.50 g/t cutoff total Measured 5,294 1.80 306 37.62 6,403 2.25 383
Indicated 6,528 1.15 240 31.01 6,509 1.52 319
M+I 11,822 1.44 546 33.97 12,912 1.85 702
Inferred 3,956 1.13 144 42.90 5,456 1.65 209
0.70 g/t cutoff total Measured 4,094 2.15 283 42.46 5,589 2.66 351
Indicated 4,603 1.38 204 35.48 5,251 1.81 268
M+I 8,697 1.74   488 38.77 10,840 2.21 618
Inferred 2,603 1.44 120 54.36 4,549 2.09 175
0.90 g/t cutoff total Measured 3,323 2.47 264 46.57 4,975 3.03 324
Indicated 3,423 1.58 174 39.46 4,342 2.06 227
M+I 6,746 2.02 438 42.96 9,317 2.54 550
Inferred 1,859 1.71 102 64.23 3,839 2.48 148
1.0 g/t cutoff total Measured 3,019 2.62 254 48.42 4,700 3.20 311
Indicated 2,895 1.70 158 41.85 3,895 2.20 205
M+I 5,914 2.17 413 45.20 8,595 2.72 516
Inferred 1,685 1.78 97 67.22 3,642 2.59 141

“We are very pleased with these results and the major increase in potential open pit material”, said Prime COO Gregory K. Liller. “The successful Prime sampling program, started in September 2019, allowed us to evaluate the tonnage and grade in areas between the unsampled outcrop and the drilled subsurface. The sampling program confirmed our belief that the mineralized zones are substantially wider than previously modeled. We believe our planned 2020 exploration program will build on this success with emphasis on three target efforts: 1) down dip and along strike in the pit areas; 2) between pits to connect them together; and, 3) the remaining 60% of Los Reyes’s undrilled structures where outcrop grab samples are similar to sample results in the Updated Resource.”

See this link for project maps and data on Los Reyes:

Management emphasizes the following four key points:

  • Los Reyes is a much larger oxide resource than historic estimates;
  • Prime’s plan of advancing to immediate production is now being delayed to conduct exploration, as recommended by Stantec, and increase the scope and size of the project;
  • A historic 2013 Preliminary Economic Assessment included test work supporting recoveries of 93% gold and 83% silver with conventional milling, gravity and carbon-in-leach.  The Updated Resource uses recoveries of 72% gold and 25% silver; and,
  • Prime believes that heap leach processing of mineralized material below certain grades, and mill/gravity/CIL processing for the rest, could provide significant upside to further expand the resource and recover more gold and silver ounces.

Updated Resource
Following is Figure 1: Los Reyes March 2020 Resource Pits showing locations of the pit areas and Table 3: Pit Constrained Resource by Deposit with a summary of resources contained in the seven neighboring pit areas:

Figure 1: Los Reyes March 2020 Resource Pits

Figure 1 is available at

Table 3: Pit-Constrained Resource by Deposit (Cutoff Grade 0.22g/t Au)

Deposit Assurance Category Tonnes
Average Au Contained Au Average Ag Contained Ag Average AuEq Contained AuEq
Grade (g/t)  (oz ‘000) Grade (g/t) (oz ‘000) Grade (g/t) (oz ‘000)
Tahonitas -El Zapote (North & South) Measured 4,576 1.15 169 17.97 2,644 1.37 201
Indicated 5,622 0.78 141 16.55 2,992 0.98 177
M+I 10,198 0.95 311 17.19 5,637 1.15 378
Inferred 2,407 0.91 70 17.17 1,329 1.12 86
Noche Buena Measured 300 1.25 12 25.93 250 1.56 15
Indicated 1,939 0.80 50 20.92 1,304 1.05 66
M+I 2,239 0.86 62 21.59 1,554 1.12 81
Inferred 1,123 0.73 26 17.34 626 0.94 34
San Miguel  East Measured 650 1.22 26 59.88 1,251 1.94 41
Indicated 1,784 0.84 48 53.09 3,045 1.48 85
M+I 2,434 0.94 74 54.91 4,297 1.60 125
Inferred 2,391 0.81 62 54.89 4,219 1.47 113
San Miguel West Measured 93 3.15 9 42.26 126 3.66 11
Indicated 379 1.51 18 20.65 252 1.76 21
M+I 472 1.83 28 24.91 378 2.13 32
Inferred 116 0.59 2 10.97 41 0.72 3
Guadalupe  East Measured 2,141 1.46 100 42.08 2,896 1.97 135
Indicated 809 0.89 23 25.26 657 1.19 31
M+I 2,950 1.30 124 37.46 3,553 1.75 166
Inferred 814 0.58 15 18.82 492 0.80 21
Guadalupe West Measured 767 0.97 24 31.51 777 1.35 33
Indicated 692 0.53 12 18.37 409 0.75 17
M+I 1,459 0.76 36 25.27 1,186 1.06 50
Inferred 243 0.30 2 15.74 123 0.49 4
TOTAL Measured 8,527 1.24 341 28.98 7,946 1.59 436
Indicated 11,225 0.81 293 23.99 8,658 1.10 397
M+I 19,752 1.00 633 26.15 16,604 1.31 833
Inferred 7,094 0.78 179 29.95 6,831 1.14 261

CIM (2014) definitions were followed for Mineral Resources.

  1. Mineral resources which are not mineral reserves do not have demonstrated economic viability. An Inferred Mineral Resource has a lower level of confidence than that applying to a Measured and Indicated Mineral Resource and must not be converted to a Mineral Reserve.
  2. All figures are rounded to reflect the relative accuracy of the estimate. The gold and silver  1.5 m composites have been capped at 25 g/t gold and  550 g/t silver (1:83 ratio Au to Ag) and modeled on 3m x 3m x 3m block size
  3. The results from the pit optimization are used solely for the purpose of testing the “reasonable prospects for economic extraction” by an open pit and do not represent an attempt to estimate mineral reserves. There are no mineral reserves on the Los Reyes. The results are used as a guide to assist in the preparation of a mineral resource statement and to select an appropriate resource reporting cut-off grade.
  4. Resource estimation by Inverse Distance Weighting algorithm cubed (IDW3) in a multiple search pass approach; and
  5. Construction of Lerchs-Grossmann pit shells using independently assessed mining extraction costs and revenue.

Updated Resource Data Input and Review
The Updated Resource is based on 463 historic drill holes and 41 of them, completed in 2015, were never utilized in previous resource estimations. The Updated Resource also includes results from the Company’s recent 5,000 metre trenching, adit and roadcut sampling program. The Company’s sampling, and the 2015 drilling data, significantly increased the information available.  The Updated Resource is contained in a technical report prepared by Stantec under National Instrument 43-101 (“NI 43-101”), which will be available on SEDAR ( under the Company’s profile within 45 days.

The Updated Resource is enabled by two 3D block models of zones identified from drill hole records and model solids of the mineralized intervals and include Los Reyes deposits El Zapote (North and South), Tahonitas, Noche Buena, Guadalupe (East and West), and San Miguel (East and West) which are contained in an area within 1 to 3 kilometres from each other.

Stantec reviewed the input data from the entire 493-hole historic database and Prime’s 5,000 metre sampling program. They performed a number of statistical analyses including histograms comparing assay results from RC drill holes with those from diamond drill core holes.  The study showed a high degree of confidence with the two data sets including comparable mean, variance, standard deviation and coefficient of variation values. In addition, the data from 17 paired core and RC holes was also analyzed with a similar high degree of confidence with the two data sets including comparable mean, variance, standard deviation and coefficient of variation values.  Stantec was able to conclude that the drilling methods used did not create any bias regarding the grade values for gold and silver.

Relevant Historic Technical Reports
In 2013, Vista Gold Corp. (“Vista”) issued a Preliminary Economic Assessment for Los Reyes which included a mineral resource estimate.  In 2017, Los Reyes was optioned from Vista by Minera Alamos Inc. (“Minera Alamos”).  Minera Alamos commissioned Tetra Tech to complete: NI 43-101 Updated Technical Report, Guadalupe de Los Reyes Gold/Silver Project, Sinaloa, México, effective February 8, 2013 and amended and restated April 16, 2018.  Prime acquired the Vista option from Minera Alamos in 2019 and retained Tetra Tech to issue: NI 43-101Technical Report, Los Reyes Gold/Silver Project, Sinaloa, México, effective May 23, 2019 and filed August 27, 2019, which is available under Prime’s profile on SEDAR.

2020 Plan for Los Reyes
Prime has submitted a permit application to initiate road building to access new areas for drilling and trenching.  In addition, the engineering team has designed a drilling program to intersect the mineralized structures below proposed pits, along strike, in areas where pits may merge together and in new areas where there is good potential to discover high grade mineralization.

The Update Resource technical report recommends additional trenching to potentially extend the mineralization in El Zapote North and South, San Miguel East and West, between San Miguel East and Noche Buena, as well as in the Tahonitas area. It is also recommended to complete a 40 hole drilling program to: 1) assess the extension of mineralization down dip below current pit bottoms; 2) test subsurface mineralization identified during trenching program; and 3) assess the continuity between ore bodies, such as El Zapote North and El Zapote South, and between San Miguel and El Zapote North. The proposed method of drilling would include both core and RC holes.

Primes currently has $1.0 million in cash which is sufficient to sustain current operations for the remainder of 2020. In order to fund the proposed 2020 program, the Company expects to engage with a strategic partner or enter the capital markets if conditions are favourable.

Qualified Persons
William A Turner, P.Geol., and A.C. (Chris) Hunter, P.Geol. prepared the Updated Resource and authored the technical report on behalf of Stantec and are independent as defined by Section 1.5 of NI 43-101.

Gregory K. Liller, Prime’s COO was responsible for the Company’s internal geologic modelling, input review and other major aspects of the Company’s sampling program. Bruce Kienlen, P.Geol., Prime’s Vice President of Exploration, contributed to the update and field sampling program data collection.  He is responsible for Company’s database management, quality control, and internal technical reporting.

Mr. Kienlen, a qualified person for the purposes of NI 43-101, has reviewed and approved the technical content in this news release.

Los Reyes Gold and Silver Project
The Los Reyes Gold-Silver Project is district scale epithermal gold-silver project in a prolific mining region of Mexico. Mineralization in the Los Reyes area is typical of low sulfidation epithermal gold/silver systems. Over $20 million in exploration and engineering has already been spent on the project over 2 1/2 decades. Previous operators completed various prefeasibility studies and plans yet held back from development due to declining gold prices. While work completed has provided sufficient understanding of resources to fast-track Los Reyes to production, the bulk of work at Los Reyes has being conducted over less than 40% of the known structures leaving significant opportunity to expand known resources.

About Prime Mining Corp (TSX.V: PRYM) (OTCQB:PRMNF)
Prime Mining is an ideal mix of successful mining executives, strong capital markets personnel and experienced local operators who have united to build a low cost, near-term gold producer at the historically productive Los Reyes project in Mexico. The location boasts a mining history spanning hundreds of years of activity alongside a stable and established regional mining infrastructure. Decades of extensive fieldwork and technical study have positioned Los Reyes to advance to gold production quickly and cost effectively.

Los Reyes holds substantial resource upside based on open extensions of known resources, 10 kilometres of undrilled strike length and at least 8 additional exploration targets.

Prime Mining has a well-planned capital structure with significant team and insider ownership. For more information please visit and follow us on Twitter, Facebook or LinkedIn.


Andrew Bowering
Chief Executive Officer

For further information, please contact:
Anthony Patterson
Investor Relations
Prime Mining Corp.
1507 – 1030 West Georgia Street
Vancouver, BC, V6E 2Y3
Telephone: (604) 428-6128
Facsimile: (604) 428-6430

Scott Koyich
President and CEO
Brisco Capital Partners Corp.
#400 – 505 8th Avenue S.W.
Calgary, AB, T2P 1G2
Telephone: (403) 262-9888
Facsimile: (403) 263-1339

Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.

Forward Looking Information
Information set forth in this document may include forward-looking statements. While these statements reflect management’s current plans, projections and intents, by their nature, forward-looking statements are subject to numerous risks and uncertainties, some of which are beyond the control of the Company.  Readers are cautioned that the assumptions used in the preparation of such information, although considered reasonable at the time of preparation, may prove to be imprecise and, as such, undue reliance should not be placed on these forward-looking statements. There is no assurance the transactions noted above will be completed on the terms as contemplated, or at all.  The Company’s actual results, programs, activities and financial position could differ materially from those expressed in or implied by these forward-looking statements.

Join Our Mailing List