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SilverCrest Files La Joya Technical Report Updated Resources & Positive Preliminary Metallurgy; Potential For High Grade Cu-Ag-Au Concentrate With Over 30% Copper

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SilverCrest Files La Joya Technical Report Updated Resources & Positive Preliminary Metallurgy; Potential For High Grade Cu-Ag-Au Concentrate With Over 30% Copper

 

 

SilverCrest Mines Inc. (TSX VENTURE:SVL)(NYSE MKT:SVLC) announce the filing of a National Instrument 43-101 compliant updated La Joya resources Technical Report (“Technical Report”) including preliminary metallurgical test results for the La Joya Property in Durango, Mexico. The Technical Report – titled “Updated Resource Estimate for the La Joya Property, Durango, Mexico” dated March 27, 2013 – has been filed on SEDAR and is available at www.sedar.com. This Technical Report supports the Company’s January 29, 2013 news release which announced the updated resource estimation.

 

 

The updated Inferred Resources(ii) and sensitivities are summarized as (refer to tables below for details);

 

 

 

 

–  Cutoff grade of 15 gpt silver equivalent   198.6 million ounces Ag Eq

(Ag Eq(i),Global Case):

–  Cutoff grade of 30 gpt Ag Eq (Base Case);  159.8 million ounces Ag Eq

–  Cut-off grade of 60 gpt Ag Eq (High Grade  100.8 million ounces of Ag Eq

Case);

–  Cut-off grade of 0.05% WO3;                75.1 million pounds (35,700

tonnes) of WO3

 

 

 

 

Silver equivalency includes silver, gold and copper and excludes lead, zinc, molybdenum and tungsten values. Ag:Au is 50:1, Ag:Cu is 86:1, based on 5 year historic metal price trends of US$24/oz silver, US$1200/oz gold, US$3/lb copper. 100% metallurgical recovery is incorporated until further information is available.

 

 

(ii) Classified by EBA, A Tetra Tech Company and conforms to NI 43-101 and CIM definitions for resources. All numbers are rounded. Inferred Resources have been estimated from geological evidence and limited sampling and must be treated with a lower level of confidence than Measured and Indicated Resources. The reported Mineral Resource is based on the 30 gpt AgEQ and 0.050% WO3 cut-off.

 

 

The Company believes that the 60 gpt Ag Eq portion of the deposit, with an estimated tonnage of 27.9 million tonnes grading 112 grams per tonne Ag Eq(i), constitutes a priority area to be examined as a potential “Starter Pit” for initial conceptual operations. A Preliminary Economic Assessment (PEA) that commenced in January 2013 will examine the Starter Pit concept in detail. The La Joya Property has excellent potential for additional resources with the deposits (Main Mineralized Trend – “MMT”, Santo Nino and Coloradito) being open in most directions. Further infill and expansion drilling has been recommended to increase and convert resources from Inferred to Indicated.

 

 
After the initial metallurgical test work was completed in 2011 at the Laboratories of Instituto Tecnologico de Saltillo, Mexico, subsequent metallurgical test work was completed in 2012 and is being continued in 2013 at ALS Metallurgy (“ALS”) in Kamloops, BC, Canada. Current results from batch cleaner flotation tests indicate that the MMT mineralization at La Joya is amenable to conventional flotation processes for production of high grade copper concentrates with high silver and gold credits. The near-surface (priority) Manto composite produced a bulk concentrate (the 3rd cleaner concentrate Cu-Ag-Au) grading up to 40% Cu, 4,780 gpt Ag and 13.1 g/t Au. Structure composite produced a bulk concentrate containing up to 38% Cu, 4,760 gpt Ag, and 9.4 gpt Au. The bulk concentrate produced from Contact Zone composite grades up to 29% Cu, 818 gpt Ag, and 18.8 gpt Au. Concentrates in excess of 25% copper are considered to be a premium product for smelter feed. The high copper grades in La Joya bulk concentrates are mostly attributable to the varied amounts of bornite, covellite and chalcocite in the tested materials.

 

 
J. Scott Drever, President stated: “The significant increase of Inferred Resources at La Joya and the identification of a potential high grade starter pit have increased the attractiveness of the project. Confirmation by preliminary metallurgical test work that a high grade, copper-silver-gold concentrate, with high recoveries of copper, silver and gold can be produced is extremely important and encourages us to push forward with our Preliminary Economic Assessment to define preliminary operating and capital parameters for the project.”

 

 

Updated Resource Estimates
The resource update for La Joya has been independently estimated by EBA Engineering Consultants Ltd., a Tetra Tech Company utilizing Company Phase I and Phase II drill results and surface sampling programs along with independently-validated historic data. Drilling to date has been relatively widespread in the Main Mineralized Trend (MMT) as well as the independent deposits of Coloradito and Santo Nino. The MMT which includes the Phase I and II drilling areas, has a length of 2.5 kilometres and an average minimum width of over 700 metres.

The La Joya resource models separate the deposits into two broad categories based on the predominant mineralogy. The first category is comprised of silver, gold and copper mineralization (Manto and Structure Zones), with lesser amounts of tungsten (WO3), molybdenum (Mo), lead (Pb), and Zinc (Zn). The second category is predominantly tungsten and molybdenum mineralization (Contact Zone) with lesser amounts of Ag, Cu, Au, Pb, and Zn. The mineralogy of these categories is often gradational and overprinted in some areas. The Manto and Structure Zones generally lies spatially above the Contact Zone and generally follows the contours of the underlying intrusive, which outcrops in several areas. The summaries of the resource estimates below show the resources attributed to each of these mineralization categories for each of the current deposits, specifically, the MMT, Santo Nino, and Coloradito.
Manto and Structure Zones Resource Summary

 

 

 

—————————————————————————-

Ag Eq(i)  Resource     Tonnage

Cut-off  Category       (000)          Ag          Au         Cu

ZONE            gpt      (ii)       (iii)         gpt         gpt          %

—————————————————————————-

MMT              15  INFERRED     120,600        23.7        0.18       0.18

——————-          ———————————————–

30                67,600        34.7        0.24       0.25

——————-          ———————————————–

60                26,100        58.5        0.30       0.42

——————-          ———————————————–

Santo Nino       15                 6,200        20.4        0.04       0.49

——————-          ———————————————–

30                 3,600        29.2        0.05       0.75

——————-          ———————————————–

60                 1,800        43.1        0.05       1.20

——————-          ———————————————–

Total            15               126,700        23.5        0.18       0.19

——————-          ———————————————–

30                71,200        34.4        0.23       0.28

——————-          ———————————————–

60                27,900        57.5        0.29       0.48

—————————————————————————-

 

—————————————————————————-

Ag Eq(i)  Resource                                       Ag Eq(i)

Cut-off  Category    Ag Eq    Ag Oz    Au Oz    Cu lbs        Oz

ZONE            gpt      (ii)      gpt    (000)    (000)     (000)     (000)

—————————————————————————-

MMT              15  INFERRED     47.9   91,900    707.9   466,500   185,800

——————-          ———————————————–

30               68.4   75,400    519.4   377,400   148,700

——————-          ———————————————–

60              109.6   49,100    255.8   240,100    92,000

——————-          ———————————————–

Santo Nino       15               64.7    4,000      8.2    66,800    12,800

——————-          ———————————————–

30               96.1    3,400      5.3    59,400    11,100

——————-          ———————————————–

60              149.2    2,500      2.9    48,300     8,700

——————-          ———————————————–

Total            15               48.7   95,900    716.2   533,200   198,600

——————-          ———————————————–

30               69.8   78,700    524.8   436,800   159,800

——————-          ———————————————–

60              112.2   51,600    258.8   288,400   100,800

—————————————————————————-

(i) Silver equivalency includes silver, gold and copper and excludes lead,

zinc, molybdenum and tungsten values. Ag:Au is 50:1, Ag:Cu is 86:1, based

on 5 year historic metal price trends of US$24/oz silver, US$1200/oz gold,

US$3/lb copper. 100% metallurgical recovery is incorporated until further

information is available.

(ii) Classified by EBA, A Tetra Tech Company and conforms to NI 43-101, 43-

101CP, and CIM definitions for resources. All numbers are rounded. Inferred

Resources have been estimated from geological evidence and limited sampling

and must be treated with a lower level of confidence than Measured and

Indicated Resources. Mineralization boundaries used in the interpretation

of the geological model is based on a cutoff grade of 15 gpt Ag Eq using

the metal price ratios described above. The reported Mineral Resource is

based on the 30 gpt AgEQ cut-off.

(iii) Manto and Structure Resource blocks and associated volumes are

exclusive of Contact Zone blocks.

 
 

 

Contact Zone Resource Summary

 

 

 

 

—————————————————————————-

Resource  Tonnage

WO3 (%)(i) Category   (,000)                     WO3 lbs    Mo lbs

ZONE         cut-off     (ii)    (iii)    WO3 %     Mo %    (,000)    (,000)

—————————————————————————-

MMT            0.025 INFERRED   60,500    0.053    0.004    70,500     4,200

——————–         ———————————————–

0.050            25,100    0.075    0.004    41,400     1,900

——————–         ———————————————–

0.095             4,400    0.109    0.002    10,600       200

——————–         ———————————————–

Santo Nino     0.025             5,200    0.040    0.008     4,600       800

——————–         ———————————————–

0.050               900    0.070    0.013     1,500       300

——————–         ———————————————–

0.095             0.750    0.101    0.011         2      0.17

——————–         ———————————————–

Coloradito     0.025            31,900    0.062    0.028    43,300    18,000

——————–         ———————————————–

0.050            18,500    0.079    0.032    32,300    11,900

——————–         ———————————————–

0.095             4,200    0.112    0.034    10,300     2,800

——————–         ———————————————–

Total          0.025            97,600    0.055    0.012   118,400    23,100

——————–         ———————————————–

0.050            44,600    0.076    0.016    75,100    14,100

——————–         ———————————————–

0.095             8,600    0.111    0.018    20,900     3,000

—————————————————————————-

(i) WO3 is based on a standard calculation of tungsten (W) times 1.26. 100%

metallurgical recovery is assumed until further information is available.

(ii) Classified by EBA, A Tetra Tech Company and conforms to NI 43-101, 43-

101CP, and CIM definitions for resources. All numbers are rounded. Inferred

Resources have been estimated from geological evidence and limited sampling

and must be treated with a lower level of confidence than Measured and

Indicated Resources. Mineralization boundaries used in the interpretation

of the geological model is based on a cutoff grade of 200 ppm W. The

reported Mineral Resource is based on the 0.050% WO3 cut-off.

(iii) Contact Zone Resource blocks and associated volumes are exclusive of

Manto and Structure blocks.

 

 

 

 

Much of the Contact Zone resource is considered to be near-surface and potentially amenable to conventional open pit mining. This zone also contains gold, silver, copper and tin (as defined by geochemistry) which may add secondary value as a result of increased metal content.

 

 

These resource estimates are based on recent and historical information collected by SilverCrest Mines and previous operators (Luismin/Goldcorp) from 1979 to present. Phase II Company drilling comprising 78 holes (25,812.65 metres), the 26 holes Phase I Company drilling (5,753.70 metres) and 18 validated historic drillholes (5,907.26 metres) were included in the geological database used as source data for the estimation. Drill hole spacing for the 122 holes (37,473.61 metres) used in the resource estimation is approximately 75 metres.

 

 

The La Joya deposits are currently interpreted to host three related styles of mineralization.

 

 

Silver-Copper-Gold (Ag-Cu-Au) mineralization is concentrated within stratiform manto-style skarn controlled along sub-horizontal bedding. Silver-Copper-Gold, Lead-Zinc and Tungsten (Ag-Cu-Au, Pb-Zn, and W) mineralization is concentrated within structurally controlled stockwork and veining related skarn. Finally, tungsten W mineralization is found within late stage retrograde skarn development along the intrusive contact. These mineralized zones are considered to be semi-continuous along strike with true widths ranging from 15 to 50 metres using a cutoff grade of 15 gpt Ag Eq. Eight near-horizontal manto style skarn (semi-continuous disseminated stratabound sulphides) have been modeled within the resource area, which are cross-cut by the stockwork zones and considered the second dominant mineralization. Please refer to News Release dated October 17, 2011 for defined types of mineralization at La Joya.

 

 

Preliminary Metallurgy

 

 
Depending on mineralization style and conditioning applied on the ALS batch cleaner flotation tests, preliminary metal recoveries to the third cleaner concentrates range from 81.4 to 87.7% Cu, 74.9 to 84.3% Ag, and 18.2 to 56.6% Au for Manto and Structure composites. For the Contact Zone composite recoveries are from 81.4 to 83.6% Cu, 45.9 to 63.7 % Ag, and 57.0 to 66.4 % Au. In general, the obtained metal recoveries and grades indicate that the La Joya (MMT) samples are amenable for the conventional flotation process with the production of a high grade copper concentrate with high silver and gold credits. Gold appears to be amenable to gravity recovery as found in the Contact Zone composite with 24% recovered. Further test work is underway to optimise gold recovery.

 

 

The Contact Zone composite was specifically designed for assessment of tungsten recoveries by gravity methods which produced marginal recoveries of 7% W03. Further test work to determine recoveries and concentration grade of W03 is recommended.

 

 

Recoveries of molybdenum from Contact Zone composite were considered in the ALS test work. The molybdenum level in the 3rd cleaner concentrate ranges from 2 to 3% at a recovery from 51.4 to 65.4%. That suggests a separate molybdenum concentrate may be produced. Further test work on molybdenum is recommended.

 

 

Comminution, grinding and abrasive test work shows the mineralized rock to be of medium hardness and mildly abrasive. Overall, preliminary results show the rock to be amenable to conventional milling. Further test work will be completed for the next phase of work.

 

 

The head grades of the composite samples are shown in the following tables. The preliminary results shown for the Baseline concentration results as well as the results of using a cyanide suppressant both indicate excellent concentration ratios for copper, silver, gold and molybdenum.

 

 
Batch Cleaner Flotation Test Results – Baseline

 

 

 

 

—————————————————————————-

Head Assay (%, gpt)

—————————————————————–

Composite             Cu           Ag           Au      AgEQ(i)           Mo

—————————————————————————-

Manto               0.34         45.0         0.15         81.7        0.004

—————————————————————————-

Structure           0.46         58.0         0.25        110.0        0.003

—————————————————————————-

Contact(ii)         0.07          4.0         0.10         15.0        0.011

—————————————————————————-

 

—————————————————————————-

3rd Cleaner Concentrate

—————————————————————–

Assay (%, gpt)                   Recovery (%)

—————————————————————–

Composite      Cu      Ag      Au AgEQ(i)     Mo     Cu     Ag     Au     Mo

—————————————————————————-

Manto        36.3   4,700    3.40   7,991   0.27   86.7   84.3   18.2   59.6

—————————————————————————-

Structure    34.3   3,980    9.45   7,402   0.17   82.7   76.7   42.4   59.7

—————————————————————————-

Contact(ii)  16.7     670   17.40   2,976   2.02   83.6   63.7   66.4   65.4

—————————————————————————-

Note: all the metal grades are based on weighted average values.

(i) Silver equivalency includes silver, gold and copper and excludes lead,

zinc, molybdenum and tungsten values. Ag:Au is 50:1, Ag:Cu is 86:1, based

on 5 year historic metal price trends of US$24/oz silver, US$1200/oz gold,

US$3/lb copper. 100% metallurgical recovery is assumed until test work is

finalized.

(ii) Contact composite was collected and analyzed to target tungsten and

molybdenum recoveries.

 

 

 

 

Batch Cleaner Flotation Test Results – with Cyanide

 

 

 

 

—————————————————————————-

Head Assay (%, gpt)

—————————————————————–

Composite             Cu           Ag           Au      AgEQ(i)           Mo

—————————————————————————-

Manto               0.34         44.0         0.17         81.7        0.004

—————————————————————————-

Structure           0.44         60.0         0.25        110.3        0.003

—————————————————————————-

Contact(ii)         0.07          4.0         0.07         13.5        0.012

—————————————————————————-

 

—————————————————————————-

3rd Cleaner Concentrate

—————————————————————–

Assay (%, gpt)                   Recovery (%)

—————————————————————–

Composite      Cu      Ag     Au  AgEQ(i)     Mo     Cu     Ag     Au     Mo

—————————————————————————-

Manto        40.1   4,780   13.1    8,883   0.26   87.7   80.7   56.6   48.0

—————————————————————————-

Structure    38.1   4,760    9.4    8,505   0.18   81.4   74.9   35.0   53.1

—————————————————————————-

Contact(ii)  28.9     818   18.8    4,243   3.05   81.4   45.9   57.0   51.4

—————————————————————————-

Note: all the metal grades are based on weighted average values.

(i) Silver equivalency includes silver, gold and copper and excludes lead,

zinc, molybdenum and tungsten values. Ag:Au is 50:1, Ag:Cu is 86:1, based

on 5 year historic metal price trends of US$24/oz silver, US$1200/oz gold,

US$3/lb copper. 100% metallurgical recovery is assumed until test work is

finalized.

(ii) Contact composite was collected and analyzed to target tungsten and

molybdenum recoveries.

 

 

 

 

The bulk copper concentrates for Baseline results produced from Manto and Structure composites show certain potentially deleterious elements for smelting such as arsenic, antimony and bismuth. An alternative to control the concentration of arsenic in the final high grade copper-silver-gold concentrate has been identified. Adding cyanide at cleaner flotation stages reduces the arsenic content (less than 1%) to acceptable market limits without sacrificing copper, silver and gold recoveries. Additional test work is in progress to assess distribution and concentration of antimony and bismuth. The Contact Zone bulk flotation concentrate has much lower concentrations of arsenic, antimony, and bismuth that are within the limits of market acceptability.

 

 
The independent Qualified Persons for the Technical Report who have reviewed and approved the contents of this news release are James Barr., P.Geo. from the consulting firm of EBA Engineering Consultants Ltd., a Tetra Tech Company and Ting Lu, P.Eng. (for Metallurgy) from Wardrop Engineering, a Tetra Tech Company.

 

 
SilverCrest Mines Inc. (TSX VENTURE:SVL)(NYSE MKT:SVLC) is a Canadian precious metals producer headquartered in Vancouver, BC. SilverCrest’s flagship property is the 100%-owned Santa Elena Mine, located 150 km northeast of Hermosillo, near Banamichi in the State of Sonora, Mexico. The mine is a high-grade, epithermal gold and silver producer, with an estimated life of mine cash cost of US$8 per ounce of silver equivalent (55:1 Ag:Au). SilverCrest anticipates that the 2,500 tonnes per day facility should recover approximately 625,000 ounces of silver and 35,000 ounces of gold in 2013 from the Santa Elena Mine. An expansion plan to be completed in early 2014 to double metals production at the Santa Elena Mine and exploration programs are rapidly advancing the definition of a large polymetallic deposit at the La Joya property in Durango State.
 

Posted March 29, 2013

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