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GLENCORE PERKOA DEPOSIT (6.72Mt @ 16.4%Zn)

12 November 2013

PERKOA DEPOSIT

 

Project Location and Access

The Perkoa Zinc mine is located in the Sanguie Province at 120km to the west of the capital city of Burkina Faso, Ouagadougou. The project is accessible via Koudougou (the country’s third largest town) by a 100km paved road and further 35km of gravel road to site.

Koudougou is linked to neighbouring states of Ivory Coast, Ghana and Togo by tarred roads and also by railway to Abidjan, capital of Ivory Coast which has sea port.

Project history

  •  Project Perkoa was discovered in 1979 by BUMIGEB with United Nations Development Program funding while tracing geochemistry of outcropping gossans.
  •  Subsequent owners of the concession include Boliden (1992-94) and Billiton (1997-1999), they confirmed the deposit’s technical quality.
  •   Prevailing conditions has not encouraged much base metal. The 2003 new Mining Code, which was attractive to foreign Mining industry   and together with the coincident improvement in metals prices, the reforms allowed the development for AIM.
  •  January 2005: Blackthorn Resources acquired 100% of the project and Snowden completed a Bankable Feasibility Study (‘BFS’) in December 2005.
  •  March 2007: Construction at the Perkoa Zinc mine commenced, following the grant of an exploitation license.
  •  July 2008, construction at Perkoa was suspended due to a decline in global metal prices.
  •  Construction and development activities resumed in December 2010 following the formation of the joint venture with Glencore International .
  •  First pour of zinc concentrate was held January 19th 2013.
  • In April 2014, Blackthorn Resources announced that it had entered into an agreement with its joint venture partner Glencore to sell its remaining 27.3% equity interest in the Perkoa Zinc Project to Glencore.
  • 16 May 2014 Blackthorn Resources announced it entered into a binding definitive sale and purchase agreement to sell its interest in the Perkoa Project and its Burkina Faso exploration licenses to subsidiaries of Glencore Xstrata Plc.

Geology

The Perkoa project area is located in the central part of the Boromo greenstone belt. The Birimian greenstone belts are renowned for their occurrences of economic gold mineralization.  The regional geology is underlined by lower Proterozoic Birimian Super group with volcanic and sedimentary rocks mainly constituted off intermediates to mafic volcanites and various tuffs. The whole is intruded by felsic magmatic bodies.

On deposit scale the west of the geology is dominated by massive or agglomeratic andesite and eastern zone is dominated by a quartz diorite intrusion. Between these two domains lie some felsic tuffs. The silicified felsic tuffs and the associated dioritic to granitic dikes host the two main orebodies. These orebodies are structurally overlain by the andesite.  The tuffaceous rocks are intruded by a quartz diorite in the footwall (east).

The foot wall ore body and hanging wall ore body that constitute the deposit are lenticular and subparallel to the steeply dipping intrusive contact that is close to it.

DEPOSIT TYPE

The Perkoa deposit is of volcanic origin and represents the only significant zinc-silver-lead massive sulphides mineralization that has been discovered in the Birimian to date. The type of mineralization is a classic volcanogenic massive sulphides (VMS) hosted by a Birimian Belt. The deposit is unusual for its high concentrations of zinc and barium mineralisation, and relatively low amount of lead and copper.

 MINERALIZATION

The main lens called the Footwall Lens dips 70 degrees to the northwest over 300 metres of strike. The Footwall Lens is between 1 and 20 metres wide and has been intersected in drilling 600 vertical metres beneath the surface. Mineralisation is well marked by massive sphalerite (zinc sulphide) and pyrite with minor pyrrhotite. A sub-parallel lens (the Hangingwall Lens) containing stringer and disseminated sulphides lies 10 to 60 metres away in the hangingwall of the main lens.

This massive sulfide ore is mainly composed of Fe-rich sphalerite (30%), pyrite (25%), barite (10%), hexagonal pyrrhotite (5%), magnetite (5%), and white mica.

Perkoa is a volcanic massive sulphides ore body and one of the richest known zinc deposits. It is metallurgically a very clean deposit.

Mineral Resource and Mineral Reserve

SRK Consulting updated the Mineral Resources estimate at the Perkoa Project. The estimate has been completed by independent consultant, in accordance with the principles of the Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves.

A high proportion of the Perkoa resource converts to reserves, with approximately 93% of the tonnes in resources converting to reserves.

Perkoa’s estimated ore reserve totals 6.3 million tonnes at a mine head grade of 13.9% zinc, containing a total of 873,400 tonnes of zinc concentrate. The ore reserve is categorised as Probable Ore Reserves is shown in the table below (using a 9% Zn cut-off).

This ore reserve was estimated as part of a mine optimization study completed in October 2009 (source company web site / press releases).

 

Category

Tonnage

Zn Grade

Contained Zn

Ag Grade (g/t)

Contained Ag

(%)

( tones)

(tones)

Measured Resource

430000

17.2

74000

41.4

18000

Indicated Resource

6290000

16.3

1027000

35.0

220000

Total Mineral Resource

6720000

16.4

1101000

35.4

238000

Category

Tonnes

Zn Grade

Contained Zn

(%)

(tones)

Proved Reserve

Probable Reserve

6300000

13.9

873000

Total Ore Reserve

630000

13.9

873000

NB: Most of the figures are modified from company public data

www.glencore.com

12 November 2013

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