Sienna strikes mineralized porphyry with gold and copper
Tue May 13, 10:36 AMCALGARY, May 13 /CNW/ - Sienna Gold Inc (SGP.V TSX Venture Exchange) is pleased to announce the results of its most recent drill program at the Igor project in Peru. This program has successfully identified porphyry-style copper and gold mineralization with the best hole producing 218 meters (m) with an average of 0.6 grams per tonne (g/t) gold and 22.3 g/t silver. All previous drill programs at Igor had mostly targeted shallow mineralized mantos and fault zones.
Dr Warren Pratt, consultant to, and director of, Sienna, comments, "We are very pleased that the porphyry model has been validated by this drilling. Despite the very large target area, and problems reaching planned depths because of drilling difficulties, one 'wildcat' drill hole cut significant oxidised gold mineralization. Importantly, this gold is hosted by porphyry and is close to surface. This is the first time porphyry mineralization has been drilled at Igor. Furthermore, 2 other drill holes, over 2 km apart, bottomed in classic porphyry, chalcopyrite-bearing veins. We now have a much better focus on the porphyry targets and will drill on much closer centers in the future. The near surface gold target at Callanquitas is particularly exciting and has great potential for a low-cost, bulk-mineable oxidised gold deposit. However, the real prize at Igor remains a major copper-gold porphyry. The porphyry is in addition to the manto resources that Sienna has already defined".
Table 1: Best Intersections
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Hole Interval Length Weighted average grade
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(m) (m) Gold (g/t) Silver (g/t)
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CA-01b 12.3 to 230.7 218.4 0.6 22.3
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66.6 to 100.3 33.7 1.8 34.4
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including 66.6 to 93.9 27.3 2.1 35.4
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including 67.7 to 70.0 2.3 3.2 44.8
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including 86.9 to 90.7 3.8 7.0 74.7
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144.9 to 157.9 13.0 1.0 127.3
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including 145.2 to 145.6 0.4 1.9 334.0
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including 154.4 to 157.9 3.5 2.2 349.8
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228.7 to 230.7 2.0 1.7 61.8
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IG-7A1 63.1 to 81.0 17.9 0.5 17.8
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including 63.1 to 64.0 0.9 6.7 214.0
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IG-7A2 38.2 to 50.3 12.1 1.7 12.2
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Including 39.3 to 41.3 2.0 6.8 24.8
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Including 50.0 to 50.3 0.3 7.0 135.0
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IG-7B1 29.8 to 96.2 66.4 0.5% zinc
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Igor is an exciting property, with widespread surface gold mineralization, mostly in bedding-parallel mantos and fault zones. It is part of a well-known copper-silver-gold mineral district (Sayapullo) that is growing in importance. Numerous drills are turning on neighbouring properties. Over 47% of the nearly 3000 surface samples previously collected by Sienna at Igor contained over 1 g/t of gold. Previous drilling at Igor defined 128,900 Indicated and 73,300 Inferred gold-equivalent ounces in mantos and faults, about half of it oxidized (Sienna press release, February 12th, 2008). Sienna plans to expand this manto/fault-hosted resource in future drilling campaigns.
The current drill program was designed to test a conceptual porphyry model based on widespread ((greater than) 3 km long) phyllic alteration of outcropping porphyry. Phyllic alteration typically forms shells around ore zones in porphyry systems. Sienna believes that a major porphyry beneath Igor drove the mineralization of the entire district. Because the porphyry target is mostly concealed beneath Cretaceous quartzites, and is very long, the planned program comprised very widely spaced 'wildcat' holes up to 500 m deep. The completed program comprised 11 holes and a total of 2,644 m (Table 2). The final hole (CA-03) is still being assayed.
The best gold results came in Callanquitas CA-01b with 218 m of mostly oxidized material averaging 0.6 g/t of gold. This includes 33.7 m at 1.8 g/t gold (Table 1). Unfortunately, the hole could not be deepened because of technical problems. The final meter gave 2.6 g/t gold, 114 g/t silver, and 0.44% copper; importantly, it also contained porphyry-style veins and the first appearance of chalcopyrite.
Other interesting intersections came from drill holes located about 2.2 km southeast of Callanquitas. Hole IG-7A1 intersected 18 m of 0.5 g/t gold and 17.8 g/t silver with other isolated sections of similar grade. This hole probably cut the southern continuation of the Tesoros fault, which has an Indicated Resource of 84,900 gold-equivalent ounces. Drill hole IG-7A2 cut 12.1 m averaging 1.7 g/t of gold and 12.2 g/t of silver. This hole also showed stronger base metal mineralization (copper and zinc).
Another interesting drill hole, IG-7B1, intersected 66.4 m of 0.5% zinc and sporadic, narrow intersections of greater than 1% lead. Of most interest were the final 8 m which revealed classic, porphyry-type veins with grades up to 0.35% copper. Chalcopyrite also appeared. Sienna concludes that this hole touched the top of porphyry copper mineralization. The high zinc may be a halo around the copper-gold zone, a typical feature of porphyries.
Table 2: Total results, excluding CA-03.
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Weighted average grade
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Gold Silver Zinc
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Hole Depth Length (g/t) (g/t) (%)
ID (m) Interval (m) (m)
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CA-01a 51.8 No intersections of interest. Drill rods lost.
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CA-01b 230.7 12.3 to 230.7 218.4 0.6 22.3
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Includes 66.6 to 100.3 33.7 1.8 34.4
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CA-02 359 55.5 to 55.9 0.35 2.6 49
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and 201.1 to 221.3 20.2 0.18 6.1
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CA-03 207.9 Assays pending.
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DO-10 323.5 306.83 to 317.90 11.07 0.14 13.8
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PI-01 126.6 8.0 to 83.3 75.3 0.16 7.8
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PI-02 222.8 56.6 to 195.8 72.8 0.2 6.4
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IG-7A1 224.2 63.1 to 81.0 17.9 0.5 17.8
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IG-7A2 283.3 38.2 to 50.3 19.1 1.7 12.2
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IG-7B1 501.2 29.8 to 96.2 66.4 0.05 5.8 0.5
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IG-7C1 113.9 No intersections of interest.
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Sampling Methodology
Cores taken from the diamond drill rig are stored in plastic core boxes and transported to the camp for detailed logging. Afterwards, the core is sent to the Company's secure site in Trujillo for cutting with a diamond saw. One half is then sent to an accredited laboratory in various sample lengths. Randy Henkle (PGeol), the Company's independent Qualified Person, completed a chain of custody review to ensure the integrity of all sample data.
Assaying Methodology
The samples were analyzed by ALS Chemex Laboratories in Lima by inductively coupled plasma atomic emission spectroscopy for silver and 33 other elements and a 30 gram fire assay technique for gold. Samples above detection limits were re-assayed using a gravimetric fire assay technique. The specific lab procedures can be found in the company's 43-101 report on the Igor property.
This press release has been reviewed and approved by Dr Warren Pratt and the Company's VP of Operations, Murray Lytle (PEng), the Company's Qualified Persons.
The TSX Venture Exchange has neither approved nor disapproved of the
information contained herein.
Statements in this press release regarding the Company's business which are not historical facts are "forward-looking statements" that involve risks and uncertainties, such as estimates and statements that describe the Company's future plans, objectives or goals, including words to the effect that the Company or management expects a stated condition or result to occur. Since forward-looking statements address future events and conditions, by their very nature, they involve inherent risks and uncertainties. Actual results in each case could differ materially from those currently anticipated in such statements.
ContactsJohn Rucci
President (403) 508-2061 or by e-mail rucci@telus.net
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