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Hutton Garnet Beaches


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Detailed Geology

The Hutton project consists of several garnet beach sand deposits located on tidewater in northern Labrador. They were initially staked in 1997 to assess placer diamond potential as a number of ultramafic dykes with kimberlitic affinities had been identified in the area. Almandine garnet has been the primary target mineral since the early stages of the project.

Archean gneisses with a general north-south sub-vertical foliation dominate the area. The metamorphic grade of the area is in the granulite facies with garnet as an important rock forming mineral, often lending a reddish hue to the hillsides. Some of these layers have up to 80-90% garnet content by volume. The Hutton beaches are the result of heavy mineral sorting by wave action on garnet-rich glacial till, producing garnet concentrations of up to 65-70%.

The Hutton Garnet Beaches

The property consists of two beaches separated by a rocky headland at the mouth of a land-locked fiord known as Miriam Lake. They are protected from the north by another headland extending past the mouth of Ryan's Bay. Seven Islands beach is about 14 km (8.7 mi) south, near Kangalaksiorvik Fiord at Seven Islands Bay.

The beaches have been the subject of numerous field programs since 1997, involving geologists and earth scientists with specialized expertise in industrial minerals, placer deposit formation, glacial processes, archeology, environmental science and mineral processing:
  • An in-depth study was conducted on the beach system regime by Dr Norm Catto, a highly respected geomorphologist with many years of experience in beach formation and glacial processes, summarized in the Beach Formation section.
  • The Prefeasibility Report and Marketing Summary (PRMS, 2004) outlined preliminary resource and reserve estimates of over 1.25 million tonnes garnet combined for South Beach, North Beach, and offshore. For more information, please visit Tonnage & Grade.
  • An underwater survey was carried out offshore near South Beach, indicating that the sea floor is flat and sandy for more than 750 metres offshore, representing an extensive and potentially significant heavy mineral sand resource.
  • The onshore areas of South and North Beaches have been extensively tested by split spoon sampling. Soil bearing capacity tests have also been conducted.
  • A bulk sample was collected from South and North Beach for beneficiation testing and market studies (~100 tonnes).
  • Several topographic, legal and archeological surveys have been completed.
  • A 5000 tonne bulk sample planned for summer 2010 has recently been released from Environmental Assessment.
  • Pilot plant location and design is now under evaluation. Revisions to the Business Plan are almost complete and will include detailed analysis of plant costs.
South Beach, the highest grade deposit, is approximately 1,950 metres in length, with about 65% garnet. The red garnet sands progress from a homogeneous, garnet-enriched zone down to a cobble-rich layer with garnet sands as a matrix (approx. 3 m. depth).

The majority of the extent of South Beach has been drilled with a split spoon sampler, to a depth generally between 3 and 5 metres (10-16'). This work was conducted to evaluate the depth and extent of the garnet sand and refine tonnage estimates released previously. A total of 72 holes were drilled at 100m intervals with side lines at 25m intervals, for a total distance of 1800 metres along the beach. Several deeper holes were attempted, but terminated at 5 metres due to physical limitations of the drill. Garnet content appears quite uniform, in keeping with relatively consistent grades previously reported over the lateral extent of the beach.

Onshore and offshore samples have been analyzed at a number of independent facilities with expertise in heavy mineral sands.

North Beach is a much larger, lower-grade resource than South Beach, extending over 2,350 metres with about 25% garnet. A total of 26 holes have been drilled to an average of 2-3 metres in depth, at an average spacing of 100m intervals along a total beach length of 2350 metres. North Beach generally appears more layered.

Seven Islands beach is a mid-bay bar system developed by dominant southward transport, essentially parallel to the shoreline, under low to moderate energy conditions. The beach is narrower and steeper than the Hutton Beaches.

The offshore areas beyond South, North & Seven Islands Beach are also elevated in garnet. An average of about 25% garnet was established below the low tide line at South Beach by sampling over almost its full length, approximately 1550 metres (5085 ft). The garnet grade of the Seven Islands offshore averages 20% garnet along its length of 1000 metres (3280 ft).

Mineral Info & Processing

The Hutton garnet is mainly pale pink to orange almandine (Fe Al garnet), with 28.6% Fe2O3, 21.5% Al2O3, 8.06% MgO & 4.90% CaO. Ancillary minerals with possible economic potential include approximately 14 wt.% titanium and titanium-iron minerals, present as discrete, rounded particles, consisting of ilmenite and rutile. Lakefield Research estimated approximately 5.0 wt.% ilmenite, 7.0 wt.% hematite/ilmenite, and 1.0 wt.% rutile, with an average of 4.12% TiO2 assayed. Further study would be needed to determine whether titanium minerals add value as a by-product. For more information on garnet and its uses, please see Mineral Info.

Mineral Processing

Many independent laboratories have conducted separation tests on the Hutton garnet sands. Mineral processing of the high grade sands has been relatively straightforward, with combinations of magnetic and gravity separation methods, screening, and sometimes electrostatic separation. High quality concentrates have been made with minimum recovery loss of total garnet, with garnet concentrate representing about 65% of the weight of unprocessed sand from South Beach. The Hutton concentrate passed requirements of the toxic leach test (US-EPA TCLP) required for marketplace acceptance in the USA.

The UBC Center for Industrial Minerals Innovations (CIMI) conducted the most extensive processing study of South Beach sand. CIMI's proposed flow sheet consists of a scalping screen, shaking table, dry high intensity rare earth magnetic separator (DHIMS), and an electrostatic separator. The resulting product achieved 93.1% garnet product with 60% weight recovery. A preliminary test of a North Beach sample produced 78% garnet concentrate with 31.9% recovery from a feed with approximately 30.3% garnet.

Mineral processing work on bulk sample material is ongoing, with a variety of waterjet concentrates prepared and tested by industry. Recent work at the Minerals Engineering Centre at Dalhousie University, Halifax, confirms that waterjet-quality product can be made with limited processing consisting of sieving, DHIMS, induced roll magnetic separation and possibly electrostatic separation. Freeport continues to evaluate and conduct market research for the garnet sands.

Site Documentation & Monitoring

Freeport has commenced a compilation of site documentation which will be used as a basis for long-term monitoring. Several beach formation and environmental consultants are involved in this work.

Photographic Record

A photographic record of site conditions over the past 10 years will be used to study any possible changes. Several observation points have been established to photograph the sites on an annual and ongoing basis. High resolution imagery, both air and satellite photos, are being used to assist in mapping the beaches and shoreline and to study any changes over time.

Topographic & Archeological Surveys

As part of site documentation, the 1999 Legal Survey was repeated to accurately map the South and North Beaches in 3 dimensions, with a high degree of precision in plan as well as in elevation. The topographic survey work was coordinated with an archeological study, and was very important as publicly available maps of northern Labrador are largely based on air photos from many years ago, and do not reflect actual site conditions. The various sets of topographic data will be analyzed and compared to evaluate any natural changes over the period between the surveys.

Offshore Marine Studies

Detailed underwater surveys have been carried out by divers in the vicinity of the South Beach, confirming that the ocean floor is predominantly flat and sandy for kilometres, and represents an extensive and potentially significant heavy mineral sand resource. Sampling of the sea bottom confirmed elevated garnet content as seen in previous results, proving that the offshore sediments are the source of the heavy minerals composing the Hutton garnet beaches.

Over the past several years, the Canadian Hydrographic Service (CHS) has conducted offshore mapping in northern Labrador. This work will greatly assist in improving site access for large-scale commercial vessels, thereby expanding the range of companies able to provide marine services. Offshore data is now being used to plan how marine vessels could best approach the beaches. It is also being coordinated with satellite imagery studies and the onshore topographical studies.

Garnet Extraction

The Hutton beaches are located in a sub-arctic region subject to pack ice for about eight months of the year. They are "bayhead" beaches, where sand built up in a "swash zone" naturally accumulates between headlands. Activity on site is expected to be two weeks up to one month in the summer on an annual basis.

As proposed production volumes are small, garnet extraction would affect only small sections of the beaches. For example, 10,000 tonnes of garnet concentrate represents approximately 0.72 hectares (1.8 acres) or 72m by 100m for a 1 metre depth of garnet sand (236' by 328' for a 3.28' depth). Physical changes due to sand removal would be temporal, as the beach would restore its shape within a matter of days.

Recovery of garnet sand does not necessitate any blasting, crushing and grinding and no chemicals are required. The sand would be moved with relatively small equipment. These activities would be largely confined to the foreshore area, which is primarily free of vegetation.

The beach deposits are produced in a high-energy surf zone and the sand itself is subsequently coarse in texture. No silt or clay, defined by the Department of Fisheries and Oceans as particles from 0.0005 mm to 0.05 mm and smaller, and known to impact fish is present.

Site contouring and reclamation approaches will be addressed in conjunction with production and processing strategies.

Conclusion

The high grades and quality of the Hutton garnet sands, complemented by transportation advantages to a Newfoundland producer serving East Coast markets, significantly contribute to the overall value of the project. Freeport is in discussions with interested parties, both end users and producers, regarding development options for the Hutton.