| |
|
 | | |
| ||
 |  | |
| | |  
Resource Estimate Assumptions
Mineralized envelopes were defined at 0.3g/t for both Piaba and Tatajuba. At Piaba, an indicator was used to define waste and mineralized zones within the mineralized envelope. Grade estimation for both deposits utilized inverse distance squared using only composites within the mineralized envelope. Estimation parameters for measured and indicated required a minimum of 2 drillholes, minimum of 4 composites and maximum of 15. Grades were estimated in 2 passes, with all composites within 15m of the block centroid for the first and within 60m for the second. A third pass which required only 1 drillhole and a minimum of 3 composites and that all composites be within 120m of the block centroid was used to estimate the inferred blocks. The resources were classified as Measured, Indicated, or Inferred based on the pass in which the block was estimated. The resource model was verified by visual inspection of the blocks and drillholes on cross-sections and horizontal sections, by comparison of the statistics of the blocks and composites, and by swath plots through the deposit. Location The Aurizona deposit occurs in the northern corner of Maranhao State, Brazil, near the coast of the Atlantic Ocean. It is a half days drive from the cities of Belem, in Para State, and Sao Luiz, in Maranhao State. Aurizona's geographic coordinates are 1°17'40" South and 45 °45'22" West. History and Previous Work Jesuit settlers are believed to have been the first to exploit gold in Aurizona area during 17th century. During the 1800s, experienced miners were brought to the area from Minas Gerais. During the last century and the early part of the 20th century, several companies carried out work in the area. In the 1950's, a variety of companies carried out geological exploration of the region. From 1978 to 1988 CESBRA, a wholly owned subsidiary of Brascan, carried out exploration to evaluate alluvial gold occurrences and started trial operations with a pilot gravity plant. In the early 1990's, UNAMGEN entered into a joint venture with CESBRA. In 1991, a regional airborne survey was conducted (magnetics, radiometrics, and photogrametry) over the Aurizona Deposit area and the surrounding area. During the period 1991 to 1993 soil sampling, ground geophysical surveying, auger drilling, and pit mapping with panel sampling were carried out. During this time, the weathered cap at Aurizona Deposit was systematically drill tested with auger, percussion, reverse circulation, and diamond drilling. The strategy is centered on the search for bulk-tonnage low-grade gold deposits amenable to open-pit mining methods. In 1997 a work program including evaluation in the NE and SW extension of the Aurizona trend was completed. The main objective of this last program was to increase the open pittable reserves of the Aurizona Deposit in the NE and SW extensions as well as in other targets of this area. The drilling program also included drilling of the main intercepts in fresh rock to evaluate the underground potential in the Aurizona trend. A total of 10,251 m of diamond drilling (89 holes) and 2,411 m of RC percussion drilling (57 holes) has been drilled on the main Aurizona zone. Drilling on satellite zones totals 11,702 m of diamond drilling (114 holes) and 2,052 m of RC drilling (35 holes). Terms of Luna's Share Purchase from Eldorado and Brascan The closing of the acquisition is expected to occur in January 2007. The conditions precedent to the closing are normal for a transaction of this nature and include:
The purchase price payable to each party is:
Geology The Project area is located in the eastern part of the Guyana Shield (São Luis Craton), which contains a number of greenstone belts and felsic to mafic intrusives. Both greenstone belts and intrusive bodies host numerous gold occurrences from Venezuela in the west, to northern Brazil in the east. Major gold deposits like Omai (50mt at 1.5g/t Au) in Guyana and Las Cristinas (200mt at 1.2g/t Au) in Venezuela, have been identified. The São Luis Craton has often been correlated with West Africa, especially the Ashanti Belt of Ghana, where prominent shear zones cutting through Proterozoic rocks host various multi-million ounces gold deposits. The surface topography in the Project area consists of rounded flat knolls which are interfingered with mangrove swamps. The land has an elevation of 2.5 to 3m above sea level. The lateritic profile is well developed and consists of a dark red, iron-rich (limonite-goethite) crust with quartz granules and grains cemented by an iron oxide matrix. The laterite has an average thickness of 4m and shows gold enrichment where it overlies bedrock mineralization. Between the laterite and saprolite there is a mottled zone; it is argillaceous and generally occurs to a depth of 6 to 10m with no preserved structures or textures. The saprolitic zone is generally 50m thick while the weathering zone can reach a medium depth of 60 to 70m and occasionally as deep as 120m. A lithogeochemical study of major and minor elements from select drill core samples was conducted by Kerrich (1996). This work identified a diverse suite of rock types ranging from ultramafic to felsic including komatiites, basalts, shoshonites and felsic rocks. Basaltic rocks predominate. A reinterpretation of the deposit geology was carried out by Luna in 2008 which classifies Piaba as an Orogenic Gold Deposit. The deposit trends ENE and is hosted in a northern hanging wall volcanic sequence. The deposit footwall is formed by a distinctive graphitic volcano-sedimentary sequence which delimits the deposit to the south. The volcanic sequence is andesitic to basaltic in composition and fine-grained and porphyritic in texture. Minimal flow tops or bases are observed, and textures show minor variation and little evidence of bedding. Hence, it is considered that the volcanic pile contains few flow features suggesting a chaotically accumulated or rapidly "dumped" tuff pile. This is common in volcanic terrains proximal to vents or as thick ash flows. Fine semi-spherulitic devitrification textures are widespread in the less altered rock indicating that prior to the hydrothermal overprint the rocks were dominantly crystal-vitric tuffs. Structure The deposit represents an ENE-trending mineralized envelope of low-grade gold mineralization in the range of 0.30 to 1.5g/t-Au with gold values locally attaining values of 30g/t-Au or higher within a major ENE-trending fault zone in the Aurizona Group. The mineralized envelope displays several flexures along its length though it is not significantly offset by faulting. There is a clear-cut stratigraphic and structural footwall to the south of the deposit defined by a sub-vertical to steeply north-dipping volcano-sedimentary package. Graded bedding, erosional channels and truncated trough bedding within the laminated sediment footwall indicate the sequence is younging to the north (normal). This is corroborated by the preferred orientation of fractures and veins observed in the garimpos, which dip approximately 85° North. Shearing occurs locally along the footwall contact. Apart from minor foliated igneous rocks, true ductile shearing is not strongly developed in the deposit and, where it occurs, is localized and confined to strongly altered lithologies which acted as slip horizons, particularly graphitic and hydrothermally altered structures. The volcanic/igneous package, and thicker beds within the footwall sediments show essentially only a healed brittle deformation. Primary devitrification textures are common. Hence, the deposit is not classed as a shear-zone gold deposit. Remnant sedimentary features such as graded bedding, erosion channels and truncated trough bedding occur on a very fine scale in the footwall sediments suggesting that no significant recrystallization or "schisting" has occurred. Garimpo exposures and archived historic pit photos clearly show that vertical structures parallel to the mineralized envelope occur at spaced intervals within the deposit. Horizontal quartz veins dominate within the mineralized envelope and in general form ladder structures representing tensional veins between the bounding vertical structures. The horizontal veins are not limited to individual adjacent vertical structures but rather extend across several verticals and occasionally extend for an unconstrained distance out into the hanging wall beyond the mineralized envelope. These observations support an extensive strike slip fault. Alteration The alteration assemblage at Piaba is classed as strong to intense, particularly in the centre of the deposit where it overprints the primary lithologies. Piaba consists of a central elongate core of shattering where initial graphitization was overprinted by a later proximal chlorite and iron-carbonate +local albitization alteration event, and a more distal chlorite-dolomite alteration with dolomitic veinlets, grading into background chlorite sub-facies greenschist regional metamorphism. The main alteration consists of graphite enrichment, chlorite +iron carbonate alteration and clay development. The graphite in the ore deposit is believed to have been sourced from the footwall sediments. Graphitization was succeeded by an intense chlorite +iron carbonate event. Iron carbonates appear related to the chlorite overprint and are zoned outwards in fractures from ankerite to siderite. Zones of white, matrix-destructive albite flooding occur locally, presumably associated with the chlorite overprint event. Silicification is rare and appears largely controlled by steep to sub-vertical interflow contacts and (coincident) sub-vertical vein zones in association with massive chlorite. Mineralization Mineralization in the Piaba area occurs in east-northeast trending, near vertical structures (Figure 7-1). The Piaba deposit and Tatajuba to the southwest have been more defined by drilling, but several other targets have also been identified. Piaba The airborne magnetic geophysical data show that the regional magnetic stratigraphy of the Aurizona Group is disrupted in the Piaba deposit which suggests that mineralization is associated with magnetite-destructive alteration. The Piaba deposit (including the East and West extensions) has a strike length of 2.9km, trending east-northeast, with the best zones developed in the Central Zone which has a strike length of 1.2km with an average width of 60m. The primary mineralization is hosted by an andesite-basalt volcanic sequence bounded to the south by a well-defined sub-vertical to north-dipping footwall formed by a distinctive volcano-sedimentary tuff sequence with graphitic-pyritic sediments. A well-defined mineralized envelope, defined by a 0.30g/t-Au cut-off, is associated with strong hydrothermal alteration and quartz veining. Mineralization does not occur tight to the footwall contact, rather it is generally located between 10 and 30m from the footwall contact. Within the mineralized envelope, there is a clear chemical and mechanical dispersion of gold at surface which caps and flanks the mineralized trend. This gold occurs at the base of the ferruginous laterite cap. This gold cap is localized to the immediate environs of the primary deposit and does not form a broad zone of surface gold distribution at Piaba. Primary gold mineralization shows a general spatial association with the graphitized andesites and diorites and the main chlorite-carbonate overprint. However, consistent with other Orogenic Gold Deposits, gold is mainly associated with quartz veining. There are two main types of quartz vein at Aurizona, Type 1 and 2. Type 1 is a milky auriferous and weakly ferruginous or sulphidic quartz, strongly fractured, without any significant alteration halo. This type is frequently seen to contain visible gold, and commonly occurs as dominantly horizontal to sub-horizontal veins within the pit walls and in vertical holes. Type 1 auriferous quartz veins extend out from the fractured and altered deposit core. Type 2 is defined by veins with a well-defined silica halo. The vein quartz is not always present, but where it occurs it forms a central core to an iron-stained and silicified halo. These zones have been observed as more than a meter in thickness where two quartz veins occur in proximity. The quartz often exhibits en echelon and boudinaged textures suggestive of extensional tectonics. This evidence, together with the garimpo exposures suggests that these veins tend to reflect the vertical controlling structures. In fresh rock, gold is associated with quartz veining and a late remobilized pyrite phase. Gold mineralization may also occur in association with disseminated pyrite in the volcanic sequence host rock or as native gold in quartz veins in late fractures. Tatajuba The Tatajuba Deposit is located 1.8km WSW from Piaba along the main Aurizona Structure (Figure 7-1). The deposit extends over an 800m strike length and, like Piaba, contains gold mineralization associated with a sub-vertical to moderately north-dipping structure nearly parallel to the Aurizona Structure. Mineralization is hosted in a mafic to ultramafic volcanosedimentary sequence, with weathering profiles similar to Piaba. Mineralization at Tatajuba is similar to Piaba although the alteration and mineralization zone at Tatajuba is more restricted and the footwall sediment contact is somewhat irregular. There is a strong weathering overprint to the alteration zones at Tatajuba, in addition to a zone of strong fracturing, infilled by graphite which has been overprinted by the later chlorite-iron carbonate fracture controlled alteration. There is an abrupt change above the base of weathering into what appears to be essentially "unaltered" andesite. The background alteration is suspected as being chlorite and albite with calcite/dolomite Infrastructure The village of Aurizona is 1.5 km north of the Project. Road access to Aurizona has been improved. From Belem to the town of Godofrena Viana, is a good, two lane, paved highway which is approximately 415 km. From Godofrena Viana to Aurizona the route is 16 km of single lane dirt road. Aurizona has a 900m long airstrip. Air access is available by way of twin engine aircraft from Sao Luis, 230 km to the SE, or Belem, 300km to the West. Furthermore, the Project has the option of barging in bulk material and equipment to a small dock, which would need upgrading, approximately 10 km east of Aurizona. Low voltage powerlines (13.8 kv) run into the village of Aurizona. These lines would need to be upgraded to in order to serve a mining operation; otherwise, power would need to be generated on site. The closest substation is at Manaus, a 41-km distribution line with a minimum 34.5 kv capacity would be required to serve the Piaba Project. Adequate water supplies exist locally. Sufficient labour exists in Aurizona and GV; however, the availability of skilled miners is limited. Busing in skilled labourers from Belem or Sao Luis is a feasible option. Full Drilling Results 
Maps and Photos 
Piaba Plan Map - Aug 6, 2008
| | | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| ©2006 Luna Gold All Rights Reserved. |  | |
)
)
)
)
)
)