Mining Intelligence and News
Papua New Guinea

Simberi Sulphide Project

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Summary

Mine TypeOpen Pit
Study CompletedPrefeasibility
Study in ProgressFeasibility
StagePermitting
Commodities
  • Gold
  • Silver
Mining Method
  • Truck & Shovel / Loader
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Mine Life... Lock
SnapshotThe Simberi Expansion Project involves an expansion of the existing Simberi mining and processing operation to allow the treatment of fresh sulphide ore, which will significantly increase gold production and extend the mine life.

Aside from the modifications to the process plant, the expansion also includes the installation of additional power generation and the construction of a new wharf to accommodate larger ships to transport the gold bearing concentrates to third parties.

As at October 2025, while Feasibility Study (FS) work continues on schedule, the funding proposals for the Simberi Expansion Project remain to be advanced, pending resolution of the amended tax assessments matter. St Barbara has continued with advancement of the FS and procurement of several long lead time items, including the ball mill procurement, the detailed design of new ball mill circuit, finalising conditions on the CEPA environmental permit and completing the construction of the camp expansion.
Related AssetSimberi Operation

Owners

SourceSource
CompanyInterestOwnership
St Barbara Ltd. 100 % Indirect
Simberi Gold Co, Ltd. (operator) 100 % Direct
The Simberi Gold Project is 100% owned by the Simberi Gold Company Limited, a wholly owned subsidiary of St Barbara Limited.

Deposit type

  • Volcanic hosted

Summary:

Simberi Island represents an eroded, deeply dissected Pliocene strato-volcano. The island developed from multiple episodes of eruptive and effusive mafic to intermediate volcanism. Volcanic flows and intrusives range from basanite, alkali basalt, trachybasalt, trachyandesite, microsyenite, trachyte and feldspar porphyry. In places these units are overlain by a fining-up sequence of coarse grits, sandstone and mudstone. Bioclastic limestone platforms unconformably overlay the volcano-sedimentary sequence. A number of raised Pliocene to Pleistocene bioclastic limestone platforms flank the volcano and provide evidence of ongoing regional uplift.

Gold mineralisation at Simberi is associated with extension and basin formation (caldera collapse) after the cessation of volcanic activity. Mineralised normal faults are seen in all deposits, and an abundance of steep structures, steep fault lineations and normal fault offsets at Simberi are consistent with extensional tectonics.

The deposits comprise oxides and sulphides, reflecting the depth of weathering and degree of erosion. Significant oxides are predominantly present in the areas of highest topography, >150m RL. Oxides may persist to lower elevations on the larger faults, but in general, are absent in the lower ground. At Sorowar and Pigiput, the supergene oxides are well developed in the strongly argillic-altered breccia units, but the overlying agglomerate/tuffaceous sandstone is only weakly weathered. These upper units are only locally affected by the argillic-alteration, indicating deposition at a late stage in the extensional/mineralisation event. Weathering/supergene alteration is best developed in the strongly altered units.

Leapfrog software was used to generate a 0.25 g/t Au grade shell for resource estimation.

Dimensions
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.

Munun 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.

Reserves

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Mining Methods

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Required Heavy Mobile Equipment

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Comminution

Crushers and Mills

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Processing

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Commodity Production

CommodityProductUnitsAvg. AnnualLOM
Gold Payable metal koz 2,047
Gold Metal in conc./ doré koz 2202,209

Operational metrics

Metrics
Annual mining rate  ....  Subscribe
Annual processing capacity  ....  Subscribe
Stripping ratio  ....  Subscribe
Waste tonnes, LOM  ....  Subscribe
Ore tonnes mined, LOM  ....  Subscribe
Tonnes processed, LOM  ....  Subscribe
* According to 2025 study.

Production Costs

CommodityUnitsAverage
Total cash costs Gold USD  ....  Subscribe
All-in sustaining costs (AISC) Gold USD  ....  Subscribe
Assumed price Gold USD  ....  Subscribe
* According to 2025 study / presentation.

Project Costs

MetricsUnitsLOM Total
Expansion CapEx $M USD  ......  Subscribe
Sustaining CapEx $M USD  ......  Subscribe
Closure costs $M USD  ......  Subscribe
Total CapEx $M USD  ......  Subscribe
After-tax NPV @ 8% $M USD  ......  Subscribe
After-tax IRR, %  ......  Subscribe
After-tax payback period, years  ......  Subscribe

Personnel

Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Oct 31, 2025
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Workforce

Aerial view:

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