The Regency Mines plc and Direct Nickel inc Joint-Venture, Oro Nickel, owns 100% of the major lateritic nickel deposit, Mambare, in Papua New Guinea (exploration licence 1390). The deposit forms a 20x6 km plateau (dwarfs better-known 7x2 km Wowo Gap Plateau) and the licence comprise 75 sub-blocks covering 242 sq km, parts of which have been explored since the 1960s. In 1999, Anaconda estimated in a 158 sq km section: 630 Mt at 0.78%Ni and 200 Mt at 1.01%Ni in the saprolitic layer; better apparent grade and topography than the Ramu project, currently under development.
JV with Direct Nickel (DNi) as technology/exploration partner:
a) An emerging world class nickel project – Mambare Papua New Guinea
b) One of the lowest capital cost technologies available for nickel laterites, DNi Nickel Processing Technology
c) Highly experienced management team
d) To create a producing nickel company that can produce up to 20k tonnes per annum of nickel within four years, expanding to 60k tonnes per annum.
Location and geology
The Mambare Plateau is an elevated 20x7 km, old land surface west of the Ajule-Kajale Range, developed on tectonite ultramafics. To the east, these ultramafics are overlain by gabbroic rocks and submarine basaltic volcanics. Kokoda and Mamba Estate to the south-west of Mambare Plateau are linked to Popondetta and Oro Bay by gravel, at first, and sealed road.
Across the top, flat surface of the plateau, and along the slopes, the weathered ultramafic bedrock has formed significant layers of lateritic and saprolitic material. The exposed weathered material has been overlain by a protective cover of volcanic ash (up to about 6m thick).
Exploration to date
The laterite bearing nickel potential of the Mambare Plateau, some 2 to 20 km north of Kokoda, has been explored intermittently since 1960.
Previous exploration was conducted by several companies in the 1960's, including: the Bureau of Mineral Resources; Homestake-Hanna Syndicate; Amax Mining (Australia) Inc.; Southern Mining & Development Co. Ltd; and PNG Nickel Ltd.
Exploration consisted of pitting and hand augering with at least one bulldozer trench being dug. Between 1960 and 1971, 240 auger holes were drilled and 56 pits and one costean dug. In 1999 Anaconda Nickel Ltd reviewed the data over a 158 sq km area of the Mambare Plateau and estimated two limonite resource potentials: 630 Mt at 0.78% nickel with a 0.5% cut-off and 200 Mt at 1.01% nickel with a 0.8% cut-off.
Much of the previous auger drilling and pitting were too shallow to test adequately the limonite ore and in many cases failed to encounter the saprolite ore or ended in mineralisation. The potential resource needs to be further evaluated with diamond drilling to test both this limonite ore and the underlying poorly tested saprolite ore. The underlying saprolite ore is suggested to be as thick as the overlying limonite ore. Geophysical techniques such as magnetics and ground penetrating radar may help better definition of bedrock rock types and thickness of laterite profiles.
2008 drilling programme
In 2008, Regency executed an initial 4000m koken drilling programme over the southern slopes of the plateau.
Drilling results show that the laterite and saprolite development is greatest mostly along shallower gradients where the right bedrock is present. Such shallow slopes are at: ridge tops, base of ridges and valley floors. Limited laterite development was found to occur on the steeper slopes where erosion and weathering rates are higher.
More drilling is anticipated over the wider area of the main plateau with broad spaced regional testing across the full plateau to define its resource potential.
Infill drilling is anticipated between the completed lines, in the three high grade zones, to further constrain the extent of mineralisation. Deeper drilling is also planned to fully assess the extent of the saprolite profile.
The large size of the 20x6 km Mambare Plateau, compared with the 7x2 km envelope of known mineralisation at the nearby Wowo Gap, gives a large potential area of mineralisation and the possibility of a significant resource.
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