The New Simberi Gold Project is 100% owned by the Simberi Gold Company Limited, subsidiary of St Barbara Mining Pty Ltd, a wholly owned subsidiary of St Barbara Limited.
On December 10, 2025, St Barbara Limited (SBL) entered into the binding agreement under which Lingbao will acquire 50% plus one share of St Barbara Mining Pty Ltd ("SBML"), a wholly owned subsidiary of SBL, that will end up owning an 80% interest in the New Simberi Gold Project.
In a separate but linked transaction, SBL and Kumul Minerals Holdings Ltd ("Kumul") have entered into a binding agreement by which a wholly owned subsidiary of Kumul will acquire a 20% interest in the New Simberi Gold Project through the establishment of an unincorporated joint venture with St Barbara Mining Pty Ltd.
St Barbara will retain a 40% attributable share in the Simberi operation.
St Barbara is targeting the end of Q3 of FY26 for completion of both the Lingbao and Kumul transactions.
Summary:
Simberi Island, the northernmost of the Tabar Group in Papua New Guinea, forms part of the Tabar-Lihir-Tanga-Feni (TLTF) island arc, with volcanism beginning around 3.7 Ma related to back-arc extension in the Manus Basin. The TLTF islands comprise high-K calc-alkaline and silica-undersaturated alkaline rocks, and regional structural trends are dominated by north-northeast and west-northwest faults. Simberi itself is approximately 9 km in diameter, with a central volcanic core of volcanic and intrusive rocks partly encircled by raised limestone reef.
Gold mineralisation occurs within an alkalic epithermal system in the eastern half of the central volcanic core, extending ~4 km north-south by 2 km east-west. Host rocks include altered and brecciated andesites, volcaniclastic rocks, tuffs, and intrusives, with mineralisation structurally controlled by faults and extension-related fractures. Two main alteration styles are recognised: early potassic-phyllic and later carbonate alteration. Oxide gold predominates at higher elevations, with sulphide-hosted gold (mainly in pyrite and marcasite) dominating deeper zones. Gold occurs as sub-microscopic inclusions in pyrite and as discrete Au-Ag tellurides or Au-Ag-Fe alloys, with pyrite the principal refractory host.
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.
Mineralisation envelopes were constrained by a 0.25 g/t Au cut-off, structural orientation disks reflecting the dominant east-southeast trend, and polylines consistent with geochemical zoning.
Weathering at Simberi is complex and non-linear, logged as oxide, transitional, or sulphide.
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.