Exploration drilling at Northgate's Stawell mine intersects high gold grades
Tuesday April 15, 7:56 pm ET
TSX: NGX AMEX: NXG
VANCOUVER, April 15 /PRNewswire-FirstCall/ -
Northgate Minerals Corporation (TSX: NGX, AMEX: NXG) is pleased to announce assay results for seven diamond drill holes in the Golden Gift 6 (GG6) exploration area at its -
Stawell Gold mine in Australia.
HIGHLIGHTS OF EXPLORATION RESULTS
- Drilling in the GG6 area, which is located within 210 metres (m) of
existing reserves, has outlined two main zones of mineralization: the
basalt contact and stockwork zones. These zones extend over 270m
along strike and over 130m in vertical height; both are open along
strike to the north. Assays from the basalt contact zone include:
- Hole MD-5267 contained two excellent intervals: the first interval
assayed 11.2 grams per tonne (g/t) gold over 21.4m including
31.4 g/t over 3.3m; the second interval assayed 11.2 g/t gold over
16.5m.
- Hole MD-5280 assayed 10.1 g/t over 11.9m.
- Hole MD-5242 assayed 7.8 g/t gold over 11.2m including 21.2 g/t
gold over 2.4m.
- A third, previously unknown zone of mineralization (a "waterloo
zone"), was discovered just east of the main basalt contact zone.
Historically, waterloo zones at Stawell have added significant ounces
by providing secondary mining zones with the same high grade
mineralization as is found in the main basalt contact mineralization.
The best intercept to date in this new mineralization assayed
15.1 g/t gold over 11.5m in Hole MD-5234.
- Northgate has allocated $7 million to fund an aggressive exploration
program at Stawell for 2008. which will focus on numerous near mine
targets that have strong potential to increase mineable reserves.
Ken Stowe, President and Chief Executive Officer, stated, "We are extremely excited with the positive GG6 drill results at our newly acquired Stawell Gold mine in Australia. These results are the first confirmation of the excellent exploration potential we saw at Stawell during the due diligence phase of our recent acquisition of Perseverance Corporation. Drilling to date indicates that the GG6 area is characterized by continuous zones of mineralization with excellent gold grades. A resource estimation will be completed in June, which should yield a significant resource in the GG6 zone. The drilling we have completed thus far comprises only a small part of an aggressive $7 million exploration plan in and around the Stawell mine, which we expect will add even more ounces to the resources by the end of 2008."
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OVERVIEW OF STAWELL GOLD MINE
Stawell is a historic goldfield that has produced approximately five million ounces of gold from both alluvial and hard rock sources dating back to the mid-19th century Victorian gold rushes. Since the commencement of modern day production in 1984 to the end of 2007, approximately 1.8 million ounces of gold have been produced from the Stawell ore body. Production for the full year 2008 is forecast to be 112,000 ounces of gold.
The dominant geological feature at Stawell is the 1.2 kilometre wide Magdala basalt volcanic dome surrounded by gold-bearing sedimentary formations. Historical mining occurs in four distinct settings: iron-rich sediments stratigraphically above the basalt; at the sediment-basalt contact; areas of sediment bounded by basalt (locally termed "waterloos"); and, in quartz lode shear structures parallelling the plunge and dip of the basalt dome. Waterloo, a historical term, refers to a mineralized zone, which lies between two lobes or flows of basalt. Historically, waterloo zones, when they occur, have added significant resources to primary zones by providing a secondary ore zone with similar grade as the main basalt contact mineralization (see Figure 1). The geologic setting of the Stawell gold deposit shows similarities to other iron formation hosted gold deposits such as Lupin, Northwest Territories and Homestake, South Dakota.
Geology of GG6
To date, GG6 drilling indicates that the zone has similar geology and geometry to the other Golden Gift ore bodies at the Stawell mine. GG6 is situated 210m beneath the Golden Gift 5 Lower (GG5L) and is interpreted to be the fault offset of this ore body, which is currently in production. The grade of the GG6 zone is similar to the previously mined Golden Gift ore blocks which contained, on average, 100,000 ounces of gold. Three zones of mineralization have been confirmed with this latest phase of drilling, which have been termed the "basalt contact", the "stockwork" and the "waterloo" zones. MD-5234 has also provided indication of a quartz style lode in the Albion schist. Further drilling is required to confirm the continuity of this mineralization.
Figure 1: 296N Cross Section Showing Position of Mineralization Zones
through Fault Blocks
www.northgateminerals.com/Theme/Northgate/files/Releases/2008/GG6_Fig1.jpg
The stockwork zone mineralization consists of pyrrhotite in weak to moderately altered host rock. Stockwork zones occur interspersed with sub-ore-grade zones of weakly altered chlorite volcanogenic or iron-rich sediment. Quartz shear zones containing graphite and chlorite alteration are also present in the stockwork zones.
The basalt contact zone mineralization is higher grade than the stockwork zone and is hosted within strongly chlorite altered volcanogenic or iron-rich sediments. Sulphide mineralization consists of coarse arsenopyrite, up to 20mm, with recrystallised pyrrhotite and minor pyrite. Quartz veins up to 0.75m wide are a common feature in the basalt contact zone, as are bands of silicification up to 1m wide.
In addition to the basalt contact and stockwork zones, a third mineralized horizon, a waterloo zone, has been intersected by holes MD-5234 and MD-5253. Gold grades in the waterloo zone are similar to those in the main basalt contact zone.
Figure 2: Stawell Mine Section (Vertical, West Looking, Longitudinal Section with Metric Grid)
www.northgateminerals.com/Theme/Northgate/files/Releases/2008/GG6_Fig2.jpg
Drilling Results in the GG6 Zone
The assay results received to date from the 2008 drill program are presented in Tables 1, 2 and 3 and drill hole locations are presented in Table 4. These holes have comparable grade and thickness to those currently being mined in the GG5L zone.
Table 1: 2008 Assay Results from GG6 Zone - Basalt Contact Zone
Mineralization
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Estimated
Downhole True
Interval Width
Hole ID From (m) To (m) (m) (m) Gold (g/t)
-------------------------------------------------------------------------
MD-5234 264.0 272.5 8.5 4.7 5.7
-------------------------------------------------------------------------
MD-5242 296.7 307.9 11.2 5.5 7.8
including 305.5 307.9 2.4 21.2
-------------------------------------------------------------------------
MD-5253 291.1 294.4 3.3 1.4 0.4
-------------------------------------------------------------------------
MD-5267 243.7 260.5 16.5 5.8 11.2
MD-5267 328.3 349.7 21.4 9.0 11.2
including 344.7 348.0 3.3 31.4
-------------------------------------------------------------------------
MD-5280 307.0 315.1 8.1 3.5 2.7
-------------------------------------------------------------------------
MD-5280 351.6 363.5 11.9 6.5 10.1
-------------------------------------------------------------------------
Table 2: 2008 Assay Results from GG6 Zone - Stockwork Zone Mineralization
-------------------------------------------------------------------------
Estimated
Downhole True
Interval Width
Hole ID From (m) To (m) (m) (m) Gold (g/t)
-------------------------------------------------------------------------
MD-5242 261.3 272.4 11.1 5.2 2.7
-------------------------------------------------------------------------
MD-5253 275.1 276.0 0.9 0.4 9.9
-------------------------------------------------------------------------
MD-5253 281.8 289.0 7.2 3.0 1.4
-------------------------------------------------------------------------
MD-5267 307.8 313.0 5.2 1.5 2.2
-------------------------------------------------------------------------
MD-5280 284.8 295.3 10.5 5.4 3.5
-------------------------------------------------------------------------
Table 3: 2008 Assay Results from GG6 Zone - Waterloo Zone Mineralization
-------------------------------------------------------------------------
Estimated
Downhole True
Interval Width
Hole ID From (m) To (m) (m) (m) Gold (g/t)
-------------------------------------------------------------------------
MD-5234 309.0 320.5 11.5 5.1 15.1
-------------------------------------------------------------------------
MD-5253 331.8 335.5 3.7 2.0 2.4
-------------------------------------------------------------------------
MD-5234 intersected a quartz structure between 236.3m and 242.1m with
5.8m at 9.1 g/t gold that is indicative of a fourth zone of
mineralization. This has been intercepted by hole MD-5234 only and is
subject to further testing. The basalt contact intercept assayed 5.7 g/t
gold over 8.5m and the previously unknown waterloo intercept assayed
15.1 g/t gold over 11.5m.
MD-5242 intersected 50m of iron-rich sediment including coarse
arsenopyrite, banded pyrrhotite and pyrite. The stockwork intercept
assayed 2.7 g/t gold over 11.1m and the basalt contact intercept assayed
7.8 g/t gold over 11.2m, including 21.2 g/t gold over 2.4m directly
adjacent to the basalt contact.
MD-5253 intersected stockwork mineralization with 7.2m of 1.4g/t gold and
a separate zone with 0.9m of 9.9 g/t gold. The basalt contact zone
intersected 3.3m of 0.4 g/t gold. Siliceous sediment in the waterloo
position intersected 3.7m of 2.4 g/t gold.
MD-5267 intersected strongly mineralized iron-rich sediment in two
separate areas including an intercept of 16.5m of 11.2 g/t gold in a
faulted sliver of basalt contact mineralization. This zone is interpreted
to be caught in a fault splay off the footwall of the Low Fault. This has
been intersected by hole MD-5267 only and is subject to further testing.
Basalt contact mineralization was also intersected from 328.3m with an
intercept of 21.4m of 11.2 g/t gold including 3.3m of 31.4 g/t gold. A
minor stockwork intercept of 5.2m of 2.2 g/t gold was also intersected.
MD-5280 intersected a strongly altered stockwork zone containing
arsenopyrite and recrystallised pyrrhotite with 10.5m of 3.5 g/t gold.
Two intercepts in the chloritic volcanogenics included visible gold on
the basalt contact margin with 11.9m of 10.1 g/t gold and 8.1m of 2.7 g/t
gold, respectively.
MD-5243 intersected a known fault and returned no significant gold
intercepts. MD-5282 was completed and assay results are pending.
Assays from holes drilled in the GG6 zone during the scoping phase of the exploration program conducted during 2007 are presented in Appendices 1 and 2. Seven of these holes intersected the high grade basalt contact zone. Upon completion of the 2008 drill program, it is expected that there will be a total of 16 intercepts into the basalt contact zone at 50m X 50m spacing.
Drilling results to date within GG6 has established that the zone is 270m in strike length and 130m in vertical height and the zone is still open down plunge to the North. The exploration team at Stawell has begun the interpretation of the drill intercepts and expects to complete a resource estimate for the GG6 area by the end of June 2008. GG6 is interpreted to be the fault offset of the GG5 reserve block and is only is 210m away.
Drilling results to date within GG6 has established that the zone is 270m in strike length and 130m in vertical height and the zone is still open for another 100m down plunge to the North. The exploration team at Stawell has begun the interpretation of the drill intercepts and expects to complete a resource estimate for the GG6 area by the end of June 2008. GG6 is interpreted to be the fault offset of the GG5 reserve block and is only is 210m away.
While the initial work in the GG6 zone has centered on the high grade basalt contact mineralization, the discovery of a potentially significant waterloo zone further east of the main basalt contact provides another high-grade zone to focus on. Potential for further upside at GG6 is promising. Multiple ore surfaces in the GG6 zone, further extension to the north and extensions at depth, and the identification of the waterloo zone all present excellent opportunities for more ounces to be discovered in the GG6 zone. As development advances in the GG5L oreblock, it will become possible to drill test another 100m of strike length do to the north of the known mineralization and explore the waterloo zone in greater detail.
Table 4: GG6 Drill Hole Collar Locations (2008 Exploration Program)
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Collar Collar
Hole ID Easting Northing Elevation Azimuth Dip Depth (m)
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MD-5234 659030.16 898048.18 -1271.84 44.1 -59.9 366.6
-------------------------------------------------------------------------
MD-5242 659030.16 898048.18 -1271.84 31.5 -64.8 380.5
-------------------------------------------------------------------------
MD-5243 659030.16 898048.18 -1271.84 26.5 -61.7 332.0
-------------------------------------------------------------------------
MD-5253 659030.16 898048.18 -1271.84 58.8 -59.1 369.3
-------------------------------------------------------------------------
MD-5267 659030.16 898048.18 -1271.84 12.4 -63.9 407.3
-------------------------------------------------------------------------
MD-5280 659030.16 898048.18 -1271.84 64.0 -58.5 530.2
-------------------------------------------------------------------------
MD-5282 659030.16 898048.18 -1271.84 37.0 -68.0 569.6
-------------------------------------------------------------------------
In
MD-5281 659030.16 898048.18 -1271.84 49.0 -66.0 Progress
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QUALITY CONTROL - ANALYSES AND SAMPLE LOCATION
Details of quality assurance/quality control procedures for sample analysis and drill hole survey methodology are reported in detail in the National Instrument 43-101 (NI 43-101) Technical Report filed on SEDAR (www.sedar.com) on March 28, 2008.
QUALIFIED PERSONS
The program design, implementation, quality assurance/quality control and interpretation of the results is under the control of Northgate's geological staff that includes a number of individuals who are qualified persons as defined under NI 43-101. Overall supervision of the program is by Steven Harper, BSc(Hons), MAusIMM, Northgate's Senior Exploration Geologist at Stawell.
Appendix 1: 2007 Assay Results from GG6 Zone Basalt Contact
Mineralization (Previously Released by Perseverance)
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Estimated
Downhole True
Interval Width
Hole ID From (m) To (m) (m) (m) Gold (g/t)
-------------------------------------------------------------------------
2007 Scoping Program
-------------------------------------------------------------------------
MD-5003 383.5 386.2 2.1 1.2 9.8
-------------------------------------------------------------------------
MD-5014 403.6 407.4 3.8 2.2 7.3
-------------------------------------------------------------------------
MD-5014 415.0 420.5 5.5 2.9 38.0
-------------------------------------------------------------------------
MD-5014 446.3 451.6 5.2 3.0 2.2
-------------------------------------------------------------------------
MD-5077A 397.1 406.0 8.9 3.5 7.4
-------------------------------------------------------------------------
MD-5078 372.8 383.1 10.3 5.8 13.0
-------------------------------------------------------------------------
MD-5094 352.8 364.1 11.3 5.6 13.1
including 360.5 364.1 3.6 23.1
-------------------------------------------------------------------------
MD-5104 349.4 355.7 6.3 3.5 9.0
including 349.4 352.7 3.3 14.7
-------------------------------------------------------------------------
MD-5139 338.0 346.5 8.5 3.0 7.7
-------------------------------------------------------------------------
MD-5139 353.3 354.5 4.7 1.9 10.9
-------------------------------------------------------------------------
Appendix 2: 2007 Assay Results from GG6 Zone Stockwork Mineralization
(Previously Released by Perseverance)
-------------------------------------------------------------------------
Estimated
Downhole True
Interval Width
Hole ID From (m) To (m) (m) (m) Gold (g/t)
-------------------------------------------------------------------------
2007 Scoping Program
-------------------------------------------------------------------------
MD-5003 338.9 351.5 15.0 7.0 1.3
including 350.6 351.5 0.9 0.5 5.6
-------------------------------------------------------------------------
MD-5014 375.5 381.4 5.9 2.9 2.8
-------------------------------------------------------------------------
MD-5077A 376.2 388.1 11.9 6.2 2.9
including 376.2 377.6 1.4 0.7 12.4
-------------------------------------------------------------------------
MD-5078 332.4 340.6 10.1 5.7 8.4
-------------------------------------------------------------------------
MD-5094 329.9 331.0 1.1 0.6 8.4
-------------------------------------------------------------------------
MD-5104 328.7 331.9 3.2 1.8 5.7
-------------------------------------------------------------------------
MD-5105 246.7 255.2 8.5 4.6 2.5
including 254.3 255.8 1.5 0.6 3.9
-------------------------------------------------------------------------
MD-5121 317.7 325.0 7.3 2.4 1.6
-------------------------------------------------------------------------
MD-5135 295.2 314.5 19.3 5.0 3.4
-------------------------------------------------------------------------
MD-5139 319.2 326.2 7.7 2.4 0.6
-------------------------------------------------------------------------
MD-5156 385 385.4 0.4 0.2 2.5
-------------------------------------------------------------------------
x x x x x x
NOTE TO US INVESTORS:
The terms "Mineral Reserve", "Proven Mineral Reserve" and "Probable Mineral Reserve" are Canadian mining terms as defined in accordance with NI 43-101 Standards of Disclosure for Mineral Projects under the guidelines set out in the Canadian Institute of Mining, Metallurgy and Petroleum (the "CIM") Standards on Mineral Resources and Mineral Reserves Definitions and Guidelines adopted by the CIM Council on August 20, 2000. The terms "Mineral Resource", "Measured Mineral Resource", "Indicated Mineral Resource", and "Inferred Mineral Resource" used in this news release are Canadian mining terms as defined in accordance with NI 43-101-Standards of Disclosure for Mineral Projects under the guidelines set out in the CIM Standards.
x x x x x x
NORTHGATE MINERALS CORPORATION is a mid-tier gold and copper producer with mining operations, development projects and exploration properties in Canada and Australia. The company is forecasting over 400,000 ounces of unhedged gold production in 2008 and is targeting growth through further acquisitions in stable mining jurisdictions around the world. Northgate is listed on the Toronto Stock Exchange under the symbol NGX and on the American Stock Exchange under the symbol NXG.
x x x x x x
FORWARD-LOOKING STATEMENTS:
This news release contains certain "forward-looking statements" and "forward-looking information" as defined under applicable Canadian and U.S. securities laws. Forward-looking statements generally can be identified by the use of forward-looking terminology such as "may," "will," "expect," "intend," "estimate," "anticipate," "believe," or "continue" or the negative thereof or variations thereon or similar terminology. Forward-looking statements are necessarily based on a number of estimates and assumptions that are inherently subject to significant business, economic and competitive uncertainties and contingencies. Certain of the statements made herein by Northgate Minerals Corporation ("Northgate") including those related to future financial and operating performance and those related to Northgate's future exploration and development activities, are forward-looking and subject to important risk factors and uncertainties, many of which are beyond the Corporation's ability to control or predict. Known and unknown factors could cause actual results to differ materially from those projected in the forward-looking statements. Such factors include, among others: gold price volatility; fluctuations in foreign exchange rates and interest rates; impact of any hedging activities; discrepancies between actual and estimated production, between actual and estimated reserves and resources and between actual and estimated metallurgical recoveries; costs of production, capital expenditures, costs and timing of construction and the development of new deposits; and, success of exploration activities and permitting time lines. In addition, the factors described or referred to in the section entitled "Risk Factors" of Northgate's Annual Information Form (AIF) for the year ended December 31, 2007 or under the heading "Risks and Uncertainties" of Northgate's 2007 Annual Report, both of which are available on SEDAR at www.sedar.com, should be reviewed in conjunction with this document. Accordingly, readers should not place undue reliance on forward-looking statements. The Corporation does not undertake any obligation to update publicly or release any revisions to forward-looking statements to reflect events or circumstances after the date of this document or to reflect the occurrence of unanticipated events, except in each case as required by law.
Source: Northgate Minerals Corporation
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OVERVIEW OF STAWELL GOLD MINE
Stawell is a historic goldfield that has produced approximately five million ounces of gold from both alluvial and hard rock sources dating back to the mid-19th century Victorian gold rushes. Since the commencement of modern day production in 1984 to the end of 2007, approximately 1.8 million ounces of gold have been produced from the Stawell ore body. Production for the full year 2008 is forecast to be 112,000 ounces of gold.
The dominant geological feature at Stawell is the 1.2 kilometre wide Magdala basalt volcanic dome surrounded by gold-bearing sedimentary formations. Historical mining occurs in four distinct settings: iron-rich sediments stratigraphically above the basalt; at the sediment-basalt contact; areas of sediment bounded by basalt (locally termed "waterloos"); and, in quartz lode shear structures parallelling the plunge and dip of the basalt dome. Waterloo, a historical term, refers to a mineralized zone, which lies between two lobes or flows of basalt. Historically, waterloo zones, when they occur, have added significant resources to primary zones by providing a secondary ore zone with similar grade as the main basalt contact mineralization (see Figure 1). The geologic setting of the Stawell gold deposit shows similarities to other iron formation hosted gold deposits such as Lupin, Northwest Territories and Homestake, South Dakota.
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