When Aldridge Minerals (AGM-V) acquired a 450-sq.-km licence in Papua New Guinea (PNG) in February 2009, it fielded three requests from majors to joint-venture the property even before any samples were taken.
That's because the giant copper-gold deposit of Ok Tedi lies 150 km to the west of Aldridge's exploration property, the Frieda River copper-gold deposit of Xstrata (XTA-L, XSRAF-O) and Highlands Pacific (HIG-A) lies 130 km to the northwest, and Barrick Gold's (ABX-T, ABX-N) Porgera gold mine is about 50 km to the east.
Aldridge believes the mineralization footprint and geological setting of its MAG1 discovery is similar to that found at Ok Tedi, in which Inmet Mining (IMN-T, IEMF-O), currently holds an 18% stake.
"So far, it looks most similar to Tedi because we do have a copper-gold porphyry with skarn mineralization around into limestone and from what I understand, about two-thirds of the ore at the Tedi mine is copper-gold porphyry and about one-third is skarn, which looks approximately like the type of mineralization that we have," Jacob Willoughby, Aldridge's president, explains in an interview.
On Jan. 4 Aldridge notified shareholders that it had discovered large-scale copper-gold mineralization in several outcrops on its 100%-owned property from sampling an area of about 2.5 km by 0.5 km last September and October.
Of 76 rock samples taken from the MAG1 mineralized zone, two samples graded between 23% and 35% copper and averaged 60 grams gold per tonne and 238 grams silver per tonne; 13 samples graded from 1% to 12.9% copper and averaged 0.44 gram gold and 9.3 grams silver; and 28 samples graded from 0.3% up to 1% copper, and averaged 0.39 gram gold and 3.8 grams silver.
The results also indicated "comparatively low" levels of arsenic and lead with the highest grade rock samples containing a maximum of 0.34% arsenic and 0.015% lead, the company noted.
Of the 357 soil samples, about 80% returned higher than 0.1 gram gold with the highest grading 2.64 grams gold. They also hit higher than 2 grams silver with the highest of 27.8 grams silver; greater than 100 parts per million (ppm) copper with the highest of 7,330 ppm or 0.733%; and greater than 500 ppm zinc, with the highest grading 14,100 ppm zinc or 1.41%.
In areas of zinc-only mineralization, one sample graded 9.13% zinc with the average of all samples grading 0.18% zinc.
About one quarter of the rock samples were collected as float because there was little outcrop available. The remaining rock samples were taken from rock chip or channel samples. Two steep, oxidized outcrop zones each covering an area of 10 metres by 20 metres were sampled with channels across the entire outcrop.
The average grade of all the channel samples was 0.45% copper and 0.29 gram gold (taken from a total of 14 samples with gold grades ranging from 0.03 gram to 1.47 grams gold and copper grades ranging from 0.2% to 2.17%.)
The main mineralized zone lies on a northwest-southeast trending ridge and its southwestern flank, at an elevation of about 1,300-1,650 metres, lies above the Logayiu River, which flows at an elevation of about 1,200 metres.
Most of the area where the samples were taken is overgrown by dense forest typical of PNG's highlands, and outcrops are sparse. Soils were collected along tracks parallel to the slopes and perpendicular to the ridge, at 50-metre spacings.
Geological mapping has revealed two diorite intrusions into a volcano-sedimentary sequence capped by carbonate, which forms a northwest-southeast ridge. The diorites appear below the carbonate on both flanks.
The company says that the carbonate seems to form the roof of the altered and mineralized diorite intrusive, and the skarn mineralization is likely situated in the carbonates near the contact zone to the diorite. Additional skarn mineralization may be present within the carbonates where they are capping the intrusive, just under the northwest-southeast ridge.
Follow-up work is planned this year including mapping, soil and rock sampling and geophysical work to determine sulphide concentrations.
A first-round drill program is being considered for later in the 2011 field season. "We would like to get back and drill there and we'd also like to do the kind of program we did on this MAG1 anomaly at the MAG2 anomaly, subject to securing adequate funding," Willoughby says.
At presstime in Toronto, Aldridge was trading at $1.67 per share. Over the last year, it has ranged between a low of 52¢ per share on July 23 and a high of $2.25 on Jan. 7.
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