?33010?
| Proven & Probable | Measured & Indicated | Inferred | |||||||
| tonnes (kt) | Au (g/t) | oz | tonnes (kt) | Au (g/t) | oz | tonnes (kt) | Au (g/t) | oz | |
| Piaba | 17,119 | 1.32 | 729,000 | 19,615 | 1.34 | 844,000 | 9,099 | 1.19 | 347,000 |
| Tatajuba | 1,554 | 1.30 | 65,000 | 1,859 | 0.94 | 56,000 | |||
| Total | 17,119 | 1.32 | 729,000 | 21,169 | 1.33 | 909,000 | 10,958 | 1.14 | 403,000 |
Resource Estimate Assumptions
- 0.3 g/t cut-off
- 20g/t cap at Piaba and a 10g/t cap at Tatajuba
- block dimensions are 10m x 10m in the xy plane and 3m on the z axis
- Piaba database consists of 172 diamond drill holes and 63 RC holes
- Tatajuba database consists of 45 diamond drill holes
- Mineral resources that are not mineral reserves do not have a demonstrated economic viability
- Resources are inclusive of Reserves
- the independent QP responsible for the mineral resource estimate is Leah Mach, CPG, of SRK Consulting, Denver
- Reserves are based on a gold price of US$750/oz;
- Full mining recovery is assumed;
- Mine reserves are diluted along mineralized boundary to block model SMU of 10mx10mx3m;
- An internal CoG of 0.35g/tAu was used on Saprolite Rock within the pit design;
- An internal CoG of 0.37g/t-Au was used on Transition Rock within the pit design;
- An internal CoG of 0.41g/t-Au was used on Fresh Rock within the pit design;
- Internal CoG determination includes metallurgical recoveries of 95% in Saprolite, 93% in Transition, and 91% in Fresh ore;
- In situ Au ounces do not include metallurgical recovery losses;
- Saprolite is rock between topography and an interpreted floor surface marking the change from highly to moderately weathered rock;
- Transition is rock between an (upper) interpreted Saprolite floor surface and an interpreted moderately weathered rock floor surface; and
- Fresh rock is rock below an (upper) interpreted Transition floor surface.
The updated resource estimate was conducted according to the same procedures used in the May 2008 resource estimate. 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 the inverse distance squared method, using only composites within the mineralized envelope. The resources were classified as Measured, Indicated, or Inferred based on the pass in which the block was estimated. Estimation parameters for measured and indicated required a minimum of 2 drill holes, 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 classification, and within 60m for the second. A third pass which required only 1 drill hole 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 resource model was verified by visual inspection of the blocks and drill holes 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 is situated in the municipality of Godofredo Viana, in Maranhão State, Brazil, near the coast of the Atlantic Ocean. It is approx 6 hrs drive from the cities of Belem, in Para State, and Sao Luis, in Maranhão State. Aurizona's geographic coordinates are 415900E; 9856930N (UTM SAD69, 23S).
History and Previous Work
Jesuit settlers are believed to have been the first to exploit gold in the Aurizona area during the 17th century. During the 1800s, experienced miners were brought to the area from Minas Gerais. During the 19th and the early part of the 20th century, several companies carried out work in the area.
In the 1950's, a number 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 (a subsidiary of Gencor, South Africa) entered into a joint venture with CESBRA. In 1991, a regional airborne survey was conducted (magnetics, radiometrics, and photogrametry) over the Aurizona deposit 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 oxide zone at the Piaba Deposit was systematically drill tested with auger, reverse circulation, and diamond drilling. The strategy 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 Piaba Deposit in the NE and SW extensions as well as in other targets of the area. The drilling program also included drilling of the main intercepts in fresh rock to test the underground potential in the Aurizona trend.
Terms of Luna's Share Purchase from Eldorado and Brascan
The closing of the acquisition occurred in January 2007. The conditions precedent to the closing were normal for a transaction of that nature and included:
- Luna obtaining all regulatory consents, approvals and authorizations, including acceptance of the proposed transactions by the TSX Venture Exchange;
- Luna completing a private placement of common shares or other securities for net proceeds of a minimum of US$ 1.5 million; and
- Eldorado and Brascan releasing any claims against each other and against Aurizona.
The purchase price payable to each party was:
- US$500,000 on closing, US$1 million on the first anniversary of the closing (Jan 2008) and US$1.5 million on the second anniversary of the closing (Jan 2009);
- Each party had the option to take either 3 million shares of Luna on Closing or US$670,000 on the second anniversary of the Closing;
- US$1 million is payable on the first, second and third anniversary of the Commencement of Commercial Production;
- Luna paid about US$225,000 to Brascan on Closing for accrued operating expenses; and
- Luna assumed a fine of approx US$1.2 million ($21,000/month for 5 years) payable to the DNPM (Departmento Nacional de Producao Mineral) for past due fees relating to exploration rights.
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 ounce gold deposits.
The surface topography in the Project area consists of rounded flat knolls which are interdigitated with mangrove swamps. The land has an elevation of 6.0 to 80 m above sea level.
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 intruded by coarse-grained granitic intrusives. The deposit footwall is formed by a distinctive 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. 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. Intrusives logged to date mainly consist of coarse-grained quartz rich granitoids and diorites.
Structure
The deposit represents an ENE-trending mineralized zone 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 the major ENE-trending Aurizona Shear Zone. 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 at the level drilled by Luna to date 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 healed brittle deformation. Primary devitrification textures are common. 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. The limited deeper holes available display better developed shear textures suggesting that the deposit lies between the brittle-ductile transition of the Aurizona Shear zone.
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 within the Aurizona Shear Zone 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 within a dilantant zone or bend within the Aurizona Shear Zone. The Piaba deposit and Tatajuba to the southwest have been well defined by drilling although only to relatively shallow levels. Several other promising targets in similar structural settings have also been identified in the immediate vicinity of the Piaba deposit.
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 2.5km, 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.
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 which are clearly visible in the pit walls. 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 can be 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 2.4 Km WSW from Piaba along the Aurizona Shear Zone (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 Shear Zone. Mineralization is hosted in a mafic to ultramafic volcanosedimentary sequence, with weathering profiles similar to Piaba albeit less deep. 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 substantially in recent years. From Belem to the town of Godofredo Viana, is approximately 415 km of good, two lane, paved Federal and State highway. From Godofrena Viana to Aurizona there is 16 km of mainly single lane laterite surfaced road. There is a small airport at Godofredo Viana suitable for use by light aircraft.
A 13.8Kv power line services the Aurizona camp and village. A separate 69Kv line is planned to serve a mining operation, as well as 100% back-up diesel generation. The closest substation is at Manaus, 41 km away.
Sufficient manual and semi-skilled labour exists in the region; however, the availability of skilled workers is limited. Busing in skilled staff from Belem or Sao Luis is an option, as well as housing staff in the town of Godofredo Viana and adjacent towns.
Full Drilling Results
- Piaba Drill Hole Assays September 29, 2008 (PDF 776b)
- Piaba Down Hole Surveys September 29, 2008 (PDF 73kb)
- Piaba Drill Collar Locations September 29, 2008 (PDF 63kb)
- Aurizona Recent Drill Results - Sept. 24, 2008 (PDF 243kb)
- Summary Recent Aurizona Drill Results - Sept. 24, 2008 (PDF 15kb)
- Luna Gold Piaba Deposit Drill Plan Map - January 15, 2009 (PDF 931kb)
Maps and Photos
Piaba Plan Map - Jan 15, 2009