Goldrock Establishes 338,000 oz Indicated and 230,000 oz Inferred Resource at Arizaro Deposit
Vancouver, British Columbia – Goldrock Mines Corp. (TSX.V – GRM)
July 8, 2013
NR 13-08
Goldrock Mines Corp. (“Goldrock” or the "Company" ) is pleased to advise that it has established a strong foundation for the future growth and possible future expansion of its Lindero project after delivering a maiden resource estimation for the Arizaro deposit, a gold-copper porphyry discovery located 3km southeast of Goldrock’s 100% owned and fully permitted developmental-stage Lindero gold deposit.
(Fig. 1 - planned Lindero infrastructure in relation to the Arizaro deposit). The Arizaro resource estimation was undertaken by Mine Development Associates (MDA) of Reno, Nevada.
The maiden Arizaro resource at the reported 0.2 g/t Au cut-off grade includes an Indicated resource of 338,000 gold ounces (30.95 Mtonnes @ 0.34 g/t Au) and an Inferred resource of 230,000 ounces (27.37 Mtonnes @ 0.26 g/t Au). Included within the reported resource is a higher grade Indicated resource at a 0.3 g/t Au cut-off grade of 205,000 ounces (13.40 Mtonnes @ 0.48 g/t Au) associated or adjacent to a magnetite breccia
(Fig. 2 - surface drill hole location map and geology).
The inclusion of the Arizaro resources has boosted Goldrock’s total contained Measured and Indicated resources to 2.548 million gold ounces and Inferred resources to 0.94 million gold ounces. The Company currently has total Proven and Probable reserves of 65.546 Mtonnes @ 0.72 g/t Au for 1,519,000 gold ounces
(see NR dated April 17, 2013 – Lindero Feasibility Study).
Paul Matysek, President and CEO, commented
“This maiden Indicated resource estimation of 338,000 ounces certainly increases our confidence that the Arizaro deposit has the potential to add significantly to the Lindero gold production profile. The recently released Lindero feasibility study projects average gold production of 128,000 oz/year over the first three years of operation, and 109,000 oz/year over the initial nine years of operation. The newly defined Arizaro resources could potentially add to the Lindero project’s mine life and annual gold production profile, enhancing an already robust project even at today’s lower gold price environment.The higher grade portion of the Arizaro resource estimate of 205,000 ounces, plus previously identified opportunities to increase the Lindero Reserve inventory totaling over 300,000 ounces, will certainly provide a solid foundation to further optimize the Lindero project in a low operating cost, capital efficient manner once the project is operational.”
Resource Estimation
The resource estimate is based on a database of 29 diamond drill core holes totaling 8,855 metres and 27 surface trenches totaling 6,568 metres. The gold and associated copper resources were modeled and estimated by evaluating the drill and trench data statistically. Utilizing the geologic interpretations developed by Goldrock and MDA, the mineral domains were interpreted on 12 east-west oriented cross sections spaced at 50 metre intervals and plan levels spaced at 8 metre intervals. Statistical analysis of the modeled mineralization established estimation parameters and grades were interpolated into a three-dimensional block model. Lithology, alteration, and gold mineral domain models were created for the Arizaro project; a unique copper model was not created. The modeling of the Arizaro Resources was performed using Gemcom Surpac® mining software.
Grade estimation is by Inverse Distance Squared with Ordinary Kriging and Nearest Neighbour estimates run as checks. Two search passes were used with a first pass maximum distance of 150 metres and a second pass maximum distance of 300 metres. Search ellipses had the long dimensions oriented due north and vertical in the south and central portions of the deposit and north-northwest and vertical in the northern portion of the deposit. Length-weighted composites honouring all mineral domain contacts, and with a maximum length of 4 metres, were used in the estimate. Estimation within each mineral domain used only those composites coded to that respective domain. For estimation and reporting purposes, the copper mineralization is constrained within the outer, low-grade gold mineral domain.
The stated resource is reported using a 0.2 g/t Au cut-off and is fully diluted to 8m x 8m x 8m blocks that are reasonable for deposits of this nature and for the expected mining conditions and methods. In consideration of the depth limits of any potential open pit mining, the Arizaro resource was limited to a bottom elevation of 3,850 metres, approximately 300 metres below the general surface.
MDA classified the Arizaro resources by a combination of distance to the nearest sample and the number of samples, while at the same time taking into account reliability of underlying data and understanding and use of the geology. There are Indicated and Inferred resources within the Arizaro deposit. The Indicated classification sample and distance criteria are a minimum of two samples lying a maximum average distance of 50 metres from the block to be estimated. All other material within the modeled mineral domains is considered Inferred. There are no Indicated resources associated with the trench data due to limited geologic data and limited Quality Assurance/Quality Control data.
TABLE 1: ArizaroMineral Resource Summary (0.2 g/t Au cut-off grade)
|
Gold Contained (ounces) |
Gold Grade
(g/t) |
Copper Grade
(%) |
Tonnage
(t) |
| Indicated Mineral Resource |
338,000 |
0.34 |
0.15 |
30,950,000 |
| Inferred Mineral Resource |
230,000 |
0.26 |
0.14 |
27,370,000 |
TABLE 2: ArizaroMineral Resource Summary (0.3 g/t Au cut-off grade)
|
Gold Contained (ounces) |
Gold Grade
(g/t) |
Copper Grade
(%) |
Tonnage
(t) |
| Indicated Mineral Resource |
205,000 |
0.48 |
0.16 |
13,400,000 |
| Inferred Mineral Resource |
62,000 |
0.43 |
0.16 |
4,510,000 |
Notes related to Arizaro Mineral Resource Summary Tables 1 and 2:
1. Mineral Resources are reported above using a 0.2 g/t Au cut-off grade. The resources reported at a 0.3 g/t Au cut off are provided only for comparison purposes.
2. Mineral Resources are fully diluted to 8 x 8 x 8 m blocks.
3. Note that Mineral Resources are not Mineral Reserves and do not have demonstrated economic viability.
4. Rounding of numbers in the Mineral Resources listed above may cause apparent inconsistencies.
TABLE 3: Lindero and Arizaro CombinedMineral Resource Summary
|
Cut off (g/tAu) |
Gold Contained (ounces) |
Gold Grade
(g/t) |
Copper Grade
(%) |
Tonnage
(t) |
|
|
|
|
|
|
| Total Measured & Indicated Mineral Resource - Lindero & Azario |
|
2,548,000 |
0.50 |
0.11 |
159,650,000 |
|
|
|
|
|
|
| Measured Mineral Resource - Lindero |
0.15 |
700,000 |
0.76 |
0.11 |
28,500,000 |
| Indicated Mineral Resource - Lindero |
0.15 |
1,510,000 |
0.47 |
0.10 |
100,200,000 |
| Indicated Mineral Resource - Arizaro |
0.20 |
338,000 |
0.34 |
0.15 |
30,950,000 |
|
|
|
|
|
|
| Total Inferred Mineral Resource - Lindero & Azario |
|
940,000 |
0.34 |
0.11 |
87,070,000
|
|
|
|
|
|
|
| Inferred Mineral Resource - Lindero |
0.15 |
710,000 |
0.37 |
0.09 |
59,700,000 |
| Inferred Mineral Resource - Arizaro |
0.20 |
230,000 |
0.26 |
0.14 |
27,370,000 |
Notes related to Arizaro Mineral Resource Summary Tables 3:
1. Mineral Resources for Lindero are reported using a 0.15 g/t Au cut-off grade.
2. Mineral Resources for Lindero are reported with internal dilution appropriate for a 10 x 10 x 8 m selective mining unit and assuming cut-off grades between 0.1 g/t and 0.5 g/t Au. No external dilution is included.
3. Mineral Resources for Lindero are reported using a long-term gold price of US$1,450/oz, mining costs at US$2.10 per tonne of material (including G&A), with total processing and process G&A costs of US$5.20 per tonne of ore and an average process recovery of 70%. The refinery costs net of pay factor were estimated to be US$6.19 per ounce gold.
4. Mineral Resources for Lindero are reported within a conceptual pit shell using a slope angle (52°) consistent with the geotechnical consultant’s recommendations (Seegmiller, August 2012).
5. Mineral Resources for Arizaro are reported using a 0.20 g/t Au cut-off.
6. Mineral Resources for Arizaro are fully diluted to 8 x 8 x 8 m blocks.
7. In consideration of the depth limits of any potential open pit mining, the Arizaro resource was limited to a bottom elevation of 3,850 m approximately 300 m below the general surface.
8. Note that Mineral Resources are not Mineral Reserves and do not have demonstrated economic viability.
9. Rounding of numbers in the Mineral Resources listed above may cause apparent inconsistencies.
Next Steps
The Company is now working towards identifying metallurgical and mine planning scenarios appropriate for the development of the Arizaro deposit as a supplement ore feed during the planned Lindero operation. Management believes that the low operating cost processing option of direct dump leaching of the lower grade ore, with selective handling of the higher grade material through the planned Lindero crushing circuit, warrants investigation. This conclusion is due to the high level of oxidation in this deposit, coupled with results from the preliminary metallurgical testing and the large amount of low grade material in the deposit. This scenario could potentially enable Goldrock to maintain a consistent 120,000 to 130,000 gold ounces per annum beyond the first 3 years using the planned Lindero infrastructure as outlined in the recently released feasibility study. In addition, the significance of the near surface intersection in drill hole ARD 03 (24 metres @ 0.70 g/t Au, 0.36% Cu), located 400 metres west of the drilling at the main mineralized zone (Fig. 2 - surface drill hole location map and geology)., merits follow up exploration.
Arizaro Background
The Arizaro porphyry body was identified prior to the discovery of the Lindero gold deposit in 1999. The Arizaro porphyry system, as defined by drilling, surface sampling and mapped alteration covers a 600 metre by 500 metre surface area. Gold-copper mineralization occurs from surface to a true vertical depth of 500 metres and remains open for expansion in all directions. The Company initially tested the discovery with 16 diamond drill holes, all of which had significant mineralized intercepts with numerous thick sections greater than 100 metres with grades greater than 0.30 g/t gold and 0.15% copper, and with one hole returning 48 metres of 1.36 g/t gold and 0.36% copper.
Qualified Person
The scientific and technical data contained in this news release has been reviewed and approved by the following Qualified Persons under NI 43-101, who consent to the inclusion of their names in this release. The Arizaro Mineral Resource estimation was completed under the supervision of Paul Tietz, C.P.G., from Mine Development Associates and the Lindero Mineral Resource estimation was completed under the supervision of David Thomas, P.Geo, from AMEC Americas Limited, who are independent Qualified Persons as defined under National Instrument 43-101. David Keough, F.AusIMM (CP), COO and a Director of Goldrock Mines Corp., is the Company's designated Qualified Person for the purposes of the Feasibility Study. Mr. Keough has reviewed and approved the scientific and technical contents of this press release while Messrs Tietz and Thomas have reviewed and approved the scientific and technical contents of this press release as they pertain specifically to the Arizaro and Lindero deposits, respectively.
ON BEHALF OF THE BOARD OF DIRECTORS,
“Paul Matysek”
Paul Matysek,
M.Sc., P.Geo
President and CEO
For additional information
About Goldrock Mines Corp.
Goldrock Mines Corp. is an emerging gold producer focused on the development of its 100% owned Lindero gold deposit located in Salta province, northwestern Argentina. The Company has been granted the primary mining permit by the Salta provincial government allowing the Company to develop the Lindero open pit, heap leach gold mine. Results of the Lindero Feasibility Study have recently been announced. Production will be at an initial throughput rate of 15,000 TPD, increasing to 18,750 TPD during the first year of operation. Average annual production will be 109,000 ounces during the first nine years. The Company has assembled an experienced operating team and is now arranging project financing with commercial production anticipated in 2015. Goldrock’s objective is to become a mid-tier gold producer with annual gold production of 250,000 ounces per year through organic growth and accretive acquisitions of near-term producing assets.
Neither the TSX Venture Exchange, nor its Regulation Services Provider accepts responsibility for the adequacy or accuracy of this release.
Caution Regarding Forward-Looking Statements
This press release includes certain statements that may be deemed “forward-looking statements”. All statements in this discussion, other than statements of historical facts, that address future exploration drilling, exploration activities, anticipated metal production, internal rate of return, estimated ore grades, commencement of production estimates and projected exploration and capital expenditures (including costs and other estimates upon which such projections are based) and events or developments that the Company expects, are forward looking statements. Although the Company believes the expectations expressed in such forward looking statements are based on reasonable assumptions, such statements are not guarantees of future performance and actual results or developments may differ materially from those in forward-looking statements. Factors that could cause actual results to differ materially from those in forward-looking statements include metal prices, exploration success, continued availability of capital and financing, and general economic, market or business conditions. Accordingly, readers should not place undue reliance on forward-looking statements.