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Ivanhoe Mines finds thick high-grades at Flatreef discovery

19th March 2014

By: Henry Lazenby

Creamer Media Deputy Editor: North America

  

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TORONTO (miningweekly.com) – Africa-focused project-development firm Ivanhoe Mines on Wednesday revealed that it had uncovered new thick high-grade mineralisation in an area that had become a new extension of the Flatreef platinum/palladium/nickel/copper/gold/rhodium discovery at the company's Platreef project, on the northern limb of South Africa's Bushveld Igneous Complex.

The TSX-listed firm reported that drill hole UMT400, recently bored in the Ga-Madiba extension zone on the eastern flank of the Flatreef extension, intersected 48.6 m that contained 4.63 g/t of platinum, palladium and gold (3PE), and 0.30% nickel and 0.13% copper, at a cutoff of 1 g/t of 3PE.

The ratio of platinum to palladium was found to be about 1:1 in the mineralised intercept, while rhodium assays were still pending. The vertical intersection had a true thickness of about 34.4 m when adjusted for the dip of the mineralised zone.

The Ga-Madiba zone, covering about 3.7 km2, adjoins and stretches to the south from the established area of Canadian National Instrument 43-101-compliant inferred resources, which, in turn, surrounds the area of indicated resources that lay at the heart of the Flatreef discovery, and where Ivanhoe is planning to develop an underground mine.

"The drill results are another highly encouraging development in the history of our discoveries at Platreef, confirming our continuing exploration priority and demonstrating additional promising potential. Significantly, the drilling has established continuity of our open-ended, Flatreef polymetallic discovery, extending its strike length to 6.5 km,” said the founder and largest shareholder of Ivanhoe Mines, chairperson Robert Friedland.

He added that the combined grade and thickness of the platinum-group and base-metals mineralisation found in UMT400 further reinforced Ivanhoe's belief that the Flatreef deposit remained open along strike for potential expansion.

"We plan to aggressively drill the area in pursuit of our objective of infilling and expanding this new discovery area," Friedland noted.

Another new drill hole in the Ga-Madiba zone – UMT409, which collared 818 m south of UMT400 – also intersected substantial mineralisation on a portion of the Flatreef.

Holes UMT400 and UMT409 were collared about 3.5 km and 4.3 km, respectively, south of the site of the planned bulk-sample shaft on the Flatreef.

The high-grade mineralisation in the T2 reef started at a depth of 967 m below the surface and continued to 1 016 m in UMT400. The mineralised reef in UMT409 was intersected at much shallower depths of 720 m to 729 m below the surface.

A total of 15 parent drill holes had been completed on about 400-metre drill centres within the Ga-Madiba area. Ivanhoe said that it intended to prepare a maiden inferred resource estimate for the Ga-Madiba area after completing ten more holes from the planned exploration programme.

Drilling to date had successfully identified the T1 and T2 mineralised reefs and had confirmed the initial interpretation that the Ga-Madiba target represents the southern strike extension to the shallow-lying Flatreef. The overall drill results’ depth, range of grade, thickness and grade-thickness were comparable to the initial, 400-m-spaced drill results in Flatreef's Zone 1, before a 100 m x 100 m indicated infill programme was completed.

TARGETS EXPANDED

The positive results of ongoing drilling at Ga-Madiba and elsewhere on the Platreef project had enabled Ivanhoe to update and expand the potential quantity and grade of mineralisation at its two primary exploration targets.

At Target 1, the Ga-Madiba extension zone now covered an area of 3.7 km2 and, based on the results of 14 drill holes completed between October 26, 2012 and February 18 this year, Ivanhoe had estimated that the target could contain between 115-million and 235-million tonnes of ore grading 1.2 g/t to 1.7 g/t platinum, 1.7 g/t to 2.3 g/t palladium, 0.17 g/t to 0.26 g/t gold, 0.06 g/t to 0.14 g/t rhodium (3.1 g/t to 4.5 g/t 4PE), 0.23% to 0.28% nickel and 0.11% to 0.14% copper. The tonnage and grades were based on intersections of 2 g/t 3PE in drill holes completed in Target 1.

At its Target 2, which surrounds the currently estimated mineral resources in zones 1 and 2 and covers an area of 7.6 km2, the company estimated that the area could contain about 260-million to 450-million tonnes grading 1.7 g/t to 2.4 g/t platinum, 1.2 g/t to 1.6 g/t palladium, 0.26 g/t to 0.33 g/t gold, 0.14 g/t to 0.20 g/t rhodium (3.4 g/t to 4.5 g/t 4PE), 0.30% to 0.35% nickel and 0.15% to 0.18% copper over an area of 7.6 km2. The tonnage and grades were based on 2 g/t 3PE intersections of mineralisation in 19 drill holes completed in Target 2 and adjacent drill holes within the inferred resources.

The company noted, however, that the potential quantity and grade of these exploration targets were conceptual in nature.

Ivanhoe noted that there were about 37 km2 of unexplored ground beyond these two exploration target areas on the property, under which the Platreef mineralisation was projected to lie, indicating “excellent potential” to significantly increase the mineralisation with further step-out drilling to the south-west.

There were currently eight drill rigs operating at the Platreef project, focused on resource delineation and expansion. In addition to the Ga-Madiba prospect, Ivanhoe was busy conducting infill drilling to potentially expand the indicated resources of the initial planned mining area to support potential production scenarios of up to 12-million tonnes a year.

Ivanhoe's previous drilling at the Flatreef Discovery produced combined intercepts of the T1 and T2 mineralised reefs that averaged 24 m in thickness at a 2g/t 4PE cut-off, which was recognised as exceptional results for the Bushveld Complex, where many underground platinum mines have average reef thicknesses of 0.4 m to 1.5 m.

BULK SAMPLE SHAFT

Meanwhile, surface construction work was under way for the 7.25-m diameter bulk-sample shaft (Shaft #1).

The vertical shaft was planned to be sunk to a depth below surface of 800 m and enable Ivanhoe to take a bulk sample at some point in the first half of 2016, to complete the company's development assessment of the Flatreef.

South Africa-based Aveng Mining, the sinking contractor for Shaft #1, was continuing surface preparation work at the site, and had started excavating the box-cut access. Further, the company was busy upgrading the hoisting equipment to be installed in the shaft headframe; excavating holes for the concrete foundations of the shaft collar; and ventilation casing were scheduled to start this month.

Ivanhoe said that it was finalising a preliminary economic assessment (PEA) of the Platreef project based on an underground mining operation of up to 12-million tonnes a year, using multiple shafts. The PEA was expected to be complete this month.

This is happening in tandem with South Africa's DRA Mineral Projects, which in consultation with Stantec, SRK, Geotail, Golder Associates and Digby Wells, was progressing with the pre-feasibility study.

Edited by Creamer Media Reporter

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