TORONTO (miningweekly.com) – Africa-focused Ivanhoe Mines on Wednesday reported that it had intersected “unprecedented” mineralisation in an exploration drill hole at its flagship South African Platreef precious metals project.

The company said it had found 4.51 g/t of platinum, palladium, rhodium and gold (4E) over 90.64 m, at a 1 g/t platinum, palladium, rhodium cutoff in Hole TMT006 at the underground Flatreef 4E/nickel/copper discovery, which is part of the company's Platreef project in South Africa's platinum-rich Bushveld Igneous Complex.

The intersection also held more nickel and copper, grading 0.37% nickel and 0.20% copper, and a platinum-to-palladium ratio of about one-to-one, over the entire 90 m intersection. Company founder and executive chairperson Robert Friedland had previously described the deposit’s copper and nickel content as being potentially enough to allow it to produce 4Es at negative cost.

"This is an extraordinary drill hole. The 90 m thickness of the intercept, which roughly is the same height as a 30-storey building, is unprecedented at Flatreef and I believe it also is without precedent in an underground platinum discovery in South Africa.

"The scale of the mineralised intercept has obvious implications for the contained platinum-group metals (PGMs) and base metals in the open-ended Flatreef polymetallic discovery. The combined grade and thickness of the PGMs and base metals mineralisation seen in this hole far exceeds anything we've previously encountered in all of our years of delineating resources on our Platreef project,” Friedland said.

The company said the gentle dips in the Flatreef discovery area meant that the drilled thickness was close to the deposit’s true thickness.

The high-grade mineralisation started at a depth of 803.43 m below the surface and continued to a depth of 894.07 m. The two mineralized reefs that comprise the uppermost mineralised portion of the Flatreef discovery — T1M and T2 — are next to each other in this area, which was a contributing factor to the size of the intersection.

Hole TMT006 was collared about 360 m south of the location of the $80-million bulk-sample shaft, which recently received approval to proceed from the South African government's Mineral Resources Department.

Previous drilling by Ivanhoe Mines at the Flatreef discovery produced combined intercepts of the T1M and T2 zones that averaged 24 m in thickness. This was exceptional for the Bushveld, where many underground platinum mines have averaged thicknesses of 0.4 m to 1.5 m.

Since drilling resumed at the Platreef project in June, a total of 24 759 m had been drilled in 22 holes and 11 deflections, representing about 70% of the planned 2013 development drilling programme. Ivanhoe expected to complete the 2013 drilling programme in mid-December, which would bring the total drilling to 709 400 m at the Platreef project since the prospecting rights for the Turfspruit and Macalacaskop licences were acquired in February 1998.

Ivanhoe intends to undertake a three-dimensional (3D) geophysical seismic survey over the Flatreef discovery before beginning site preparation work for the bulk-sample shaft. The seismic survey is expected to begin this week and would be complete early in November.

Terrace and collar designs for the 7.25-m-diameter bulk-sample Shaft 1 had started and contractor mobilisation and site preparation were expected to start in December, once the preliminary results from the 3D survey had been received.

About 250 contract employees would be working on the 800-m-deep shaft once the sinking work begins, raising the number of people employed at the Platreef project to 550. The vertical shaft would facilitate Ivanhoe collecting a mineralised bulk sample in the second half of 2015 to complete the company's development assessment of the Flatreef.

Shaft 1 construction would be funded from the $180-million in dedicated funds remaining in Ivanhoe's treasury from the $280-million received in 2011 from a Japanese consortium of Itochu Corporation, Japan Oil, Gas and Metals National Corporation and JGC Corporation for an 8% interest in the Platreef project.