Summary:
The Simberi Gold Project is located on Simberi Island in the Tabar Islands Group situated in the New Ireland Province of Papua New Guinea (PNG), approximately 80 km north-west of Lihir Island. Simberi is the oldest and northernmost island of the Tabar Group. It measures approximately 10 km east-west, 8 km north-south and rises to over 300 m above sea level. The currently known gold prospects (Sorowar, Pigiput, Pigibo, Botlu, Pigicow, Samat, Bekou and Monun Creek) on Simberi Island are located in the eastern half of the island within the central volcanic core. They are contained within a sub-cropping epithermal alteration system and structural corridor extending 4km north-south and 2km east-west. The host rocks for the mineralisation comprise Pliocene altered alkaline lava flows or intrusives (porphyries), volcaniclastics and tuffs.
Of the eight separate deposits, Pigiput in the south is by far the largest gold resource. Monun Creek is located immediately to the north-east of Pigiput, with Sorowar, the second largest resource, further north again. Pigibo, Botlu, Samat and Bekou lie to the west and south of Pigiput, and while relatively small, are relatively higher grade. All deposits lie within 2 to 3km of each other. Sorowar, Pigiput and Botlu are currently being mined via open pit methods.
Fine grained free gold in oxide material is the target of current operations. Within the sulphide zone gold is also fine grained (most grains are under 15 µm in diameter) but is generally within pyrite. Modifications are required to the current processing plant to allow flotation of pyrite and recovery of the gold.
The grade of the mineralisation is related to the natural porosity and degree of fracturing of the host rocks, greatest in the vicinity of steep and moderately dipping feeder structures interpreted to have been the pathways for both alteration and mineralising fluids.
Gold does have lithological and structural controls, but these controls are complex and cannot be easily used to generate domains for resource estimation. Leapfrog software was used to generate a 0.25 g/t Au grade shell for resource estimation. A grade shell is needed to avoid smearing grades between mineralized and essentially unmineralized areas. This grade shell is sufficiently below the resource reporting cut-offs to not introduce any significant conditional bias during resource estimation.
Oxidation domains (oxide, transitional and sulphide (fresh)) are based on logging from drill holes. The domains were defined in Leapfrog by a combination of offset surfaces and solids. The offset surfaces utilise the logging and depth below topography to create geologically realistic oxidation surfaces. The modelling of oxidation solids in Leapfrog was also required because a single oxidation surface could not always model the observed spatial complexity. For example, there can be pods of oxide completely enclosed by sulphide and vice versa.
Based on statistical analysis and contact plots the 0.25 g/t Au grade shell was subdivided into two zones for the estimation of gold grades; a combined oxide and transitional zone and a sulphide only zone.
The northernmost deposit is Sorowar, its bulk is aligned SE-NW (1,550 m) with minor (structurally controlled) orthogonal splays towards the southwest and northeast. These splays are less than 750 m long and 300 m wide.
Pigibo is oriented W-E for approximately 740 m with a central bulge about 300 m wide and tapering to about 100 m at the western and eastern extremities. It is located about 1,500 m to the southwest of the central part of Sorowar.
Pigiput is east of Pigibo and about 1000 m south of Sorowar. It is roughly equidimensional (640 m diameter) in plan.
Monun Creek is between Pigiput and Sorowar however, there is now enough drilling to define continuous mineralisation between Pigiput and Sorowar.
Botlu is about 800 m south of Pigibo. It strikes SE-NW for approximately 680 m with an average width of around 250 m. About 700 m to the SE of Botlu is the discontinuous Pigicow deposit which strikes SW-NE for nearly 600 m with a variable width (200-450 m).
Samat is located about 700 m to the southeast of Pigicow and is aligned north-south for approximately 720 m with an average width of 300 m. Like Pigicow, Bekou is discontinuous and oriented towards the east-northeast with a strike length of around 600 m. Located about 650 m to the southwest of Samat, its width varies from 40 m to 170 m.