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Buckreef Gold Mine Re-Development Project
The Buckreef Gold Mine Re-Development Project was acquired from the Tanzanian State Mining Company (Stamico) in December 2010. Under a Heads of Agreement concluded with the state-owned company, Tanzanian Royalty has the right to earn a 55% interest in Buckreef with Stamico holding the remainder.
The Company’s August 2012 NI43-101 Preliminary Economic Assessment Report for the Buckreef Project is available by clicking the following link
The Buckreef Project is located in north-central Tanzania immediately to the south of Lake Victoria and 110km southwest of Mwanza. Access to the Buckreef project is by ferry across Smiths Sound and then via unpaved roads and an onsite airstrip. The project area comprises the dormant Buckreef Gold Mine and four prospects with known mineralization: Buckreef, Buziba, Tembo and Bingwa.
The following table details the resources that occur within the four principal deposits in the Buckreef Project area:
Geology and Mineralization
The Buckreef and Buziba gold deposits are classified as medium grade orogenic gold deposits hosted by mafic volcanic sequences of the east-west trending Archaean Rwamagaza Greenstone Belt (RGB) within the Lake Victoria Goldfields (LVG) of the Tanzanian Craton. The Buckreef deposit is hosted by a steeply dipping, northeast-southwest trending brittle-ductile shear zone. The Buziba deposit is located 25km east of the Buckreef prospect. Gold mineralization at Buziba is associated with quartz vein arrays that occur in altered shear zones in mafic rocks and as extensive stockworks in the felsic porphyries.
Regional Geological Setting
The Buckreef Project is situated within the LVG of northern Tanzania which consists of a number of east-west trending, linear, Archaean greenstone belts. The LVG is the third largest gold producing region of Africa, surpassed only by the Witwatersrand Basin in South Africa and the Tarkwa region of Ghana. Numerous gold occurrences have been identified in the LVG and new discoveries continue to be made. Since 1998, when the first mine, Golden Pride was commissioned, four additional large scale mines namely, Geita, Bulyanhulu, North Mara, and Tulawaka have come into commercial production. Geita and Bulyhanulu are considered world-class deposits, together representing in excess of 35Moz of gold resources.
The greenstone belt sequences have geological and structural similarities to major gold districts in the Canadian Shield (Val d´Or, Kirkland Lake) and the Yilgarn Craton in Western Australia (Kalgoorlie, Laverton, Leonora, Kambalda and Southern Cross).
Gold mineralization within the LVG occurs in a number of styles including:
- quartz veins within minor brittle lineaments, most commonly worked on a small scale by artisanal workers due to their limited extent and erratic gold distribution;
- mineralization within major ductile shear zones;
- mineralization associated with the replacement of iron formation and ferruginous sediments;
- and porphyry hosted mineralization such as within the Rwamagaza Greenstone Belt.
Regardless of the geological environment, it is accepted that structural control on the emplacement of the mineralization is critical. That being said, the following structural features have proven to be important foci of gold mineralization:-
- structural lineaments trending at 120º;
- flexures and splays to the 120º trend (such as at Golden Pride);
- structural lineaments at 70º (such as at Golden Ridge);
- and granite-greenstone contacts (such as at the Ushirombo and RGB).
Local Geological Setting
The Buckreef Project area covers the eastern portion of the east-west trending RGB which forms part of the Sukumaland Greenstone Belt (SGB). Aeromagnetic data and minor outcrop indicate the presence of a number of elongate discontinuous, sheared ultra-mafic bodies which could represent either intrusive bodies or the cumulate portions of thick, magnesium-rich basaltic lava flows.
Large batholithic granites intrude the RGB and the possibility exists that the RGB forms part of a much larger belt that has been dissected by the intrusions. Aeromagnetic surveys over Buckreef indicate the presence of granites at depth.
The tectonic evolution of the RGB is very poorly understood. Aeromagnetic data reveals several generations of crosscutting, late stage, brittle-ductile faults and shears which offset flow stratigraphy and have locally been intruded by the felsic porphyries and by a late stage dolerite dykes.
The weathering profile across the belt is relatively shallow across both Buckreef and Buziba Prospects. The RGB, in general, is covered by a thin layer of alluvial regolith which is amenable to standard soil sampling techniques.
The Buckreef Gold Mine was an underground mine operated by the Tanzanian State during the late 1980s. Apart from the state, several previous owners of the project undertook numerous exploration programs including aeromagnetic, helicopter-borne IP, ground magnetic and soil geochemistry surveys, as well as extensive Reverse Circulation and diamond drilling programs.
Iamgold Corporation, the former and most recent owner of the project, verified the historic drilling data, undertook additional exploration and defined Joint Ore Reserves Committee (JORC) compliant Mineral Resources in 2006.
In total, the exploration program included approximately 30,000 soil samples, 202,000m of RC drilling, 124,000m of AC drilling and 28,000m of diamond core drilling. An unconfirmed estimate for the historic exploration expenditure is U.S. $23 million. However, an estimated $45 million has been expended on Buckreef for all phases of exploration and development since the 1980s.
Metallurgical test work programs were undertaken on both the Buckreef and Buziba mineralization types. The test work on Buckreef mineralization indicated that oxide and transitional mineralization types were amenable to treatment using typical carbon-in-leach (CIL) processing techniques and fresh mineralization may benefit from flotation and a finer grind with recoveries anticipated to be in the low 90%s.
The test work results for Buziba mineralization indicated that it is amenable to treatment using gravity and CIL processing techniques. Metallurgical recoveries for Buziba mineralization were anticipated to be in the low to mid 90%s. Heap leaching test work indicated that, at a 25mm-50mm crushing size fraction in oxide mineralization, a 75% recovery could be anticipated, whilst transitional and fresh mineralization recoveries were lower, at 35% to 50%.
The Company plans to initiate a Preliminary Economic Assessment (PEA) and contingent on the successful outcome of the PEA, to undertake a definitive feasibility study as part of the process to fast track the project to production.
Since December 2010, the Company has completed preliminary due diligence of previous exploration work, completed preliminary planning on expansion and follow-up exploration programs and has commenced undertaking further exploration activities on the Buckreef Project as briefly summarized for each prospect below.
The Buziba Prospect is located approximately 20km east of Buckreef and the gold mineralisation is also similarly hosted in pillowed mafic rocks intruded by a suite of feldspar porphyry dyke slivers. Of immediate interest to the Company is the presence of a surficial laterite-cemented quartz rubble deposit previously targeted by artisanal miners.
In 1986 Madini, a section of the geological survey of Tanzania conducted a pitting program in the western part of the Buziba license which was then owned by STAMICO. The program identified a high-grade gold-bearing gravel bed with an average grade of 13.63g/t gold and an average thickness of 1m that remains open-ended to the east. Follow up exploration intends to test the area to the east with pitting program consisting of 50 pits covering an area of 1.5 sq.km. The program is expecting to generate >100 samples for gold assaying and other laboratory test work including gold deportment studies, bottle roll test etc. Grab sampling is ongoing and a total of 11 samples were collected from illegal miners’ pits and have been sent to the lab for analysis.
Bingwa lies at the northern margin of the RGB adjacent to a shared contact with a granitic intrusive and approximately 4km east of Buckreef. Gold mineralisation, associated with quartz veining in strongly foliated and altered greenstone in a shear zone abutting the granitoid contact, has been identified by drilling over a strike length of 350m and up to 100m below the surface with the main zone of mineralisation occurring over a strike length of 150m.
The majority of the mineralization defined to date lies in the oxide zone, which extends to 40 to 60m below surface. An additional 1,500m of RC and 180m of diamond core drilling are planned to commence in mid-November 2011. The RC drilling will test the southwest strike and potential down-dip extension of the main Bingwa deposit while the core drilling is to accommodate additional metallurgical and specific gravity analytical test-work.
Eastern Porphyry Prospect
The Eastern Porphyry Prospect is located on the strike extension of the east-northeast/west-southwest trending, 5-30m wide, brittle-ductile fault zone within relatively under-formed mafic volcanics immediately east of the main Buckreef Mine. Previous wide-spaced exploration drilling defined the presence of finely disseminated pyrite and quartz veining slivers of persistent but discontinuous sub-parallel zones of quartz porphyry units hosted in the main fault zone. Previous RC drilling intersected a 300m strike length of continuous gold mineralization associated with quartz veins emplaced in sheared felsic porphyry and dolerite.
The geometry of the mineralized zone is not well defined and understood at the present time. A program of infill diamond and RC drilling is planned to upgrade the target to a resource category and include it in the Buckreef Resource inventory. Diamond drilling is also expected to provide essential structural information which will be used to guide future drill programs.
The Tembo Prospect, located in an adjacent but sub-parallel shear zone to the regional east-northeast/west-southwest trending Rwamagaza main shear zone, lies approximately 3km south-west of the main Buckreef Mine. Gold mineralization at Tembo is hosted within grey quartz stringers, veinlets and boudins (tension zones) all tightly constrained by east-west shears hosted in basaltic volcanic units. Additional diamond drilling for metallurgical and specific gravity tests is planned along with three holes that are designed to upgrade the deposit resource from inferred to measured + indicated category. The drilling will also test strike continuity of mineralization to the east.