Summary:
The May 2024 Study includes the following deposits: at the Bulong Mining Centre, the Myhree and Boundary open pits and the Myhree underground; at the Mt Monger Mining Centre, the Fingals Fortune, Fingals East, Jones Find, and Crown open pits, as well as the Majestic and Fingals Fortune undergrounds. The production profiles and mining sequences may adjust in future studies as further infill and extension drilling is conducted. For instance, the already extensive Fingals Fortune deposit remains open in all directions and at depth.
Myhree
A well-developed laterite zone, up to 25m thick, sits above the local sequence which consists of (from footwall to hangingwall): komatiitic ultramafic, interlayered dolerite and volcaniclastic sediments (with variable black shale lenses), komatiitic ultramafic, and then into polymictic conglomerate with intruded dolerite lenses.
The footwall of Myhree is characterised by a zone of heavy chlorite alteration within the footwall ultramafic, generally following the trend of the ultramafic-diorite contact. Abutting the chlorite alteration is a package of highly silicified rocks generally consisting of the diorite and volcaniclastic sediments. The silicification can however cross into the footwall ultramafic, producing a bleached and highly competent rock. Above the silicified zone, the hangingwall ultramafic is characterised by talc-carbonate alteration. Finally, the conglomerate also appears to be highly silicified.
Boundary
The Boundary deposit is hosted within NNE trending, west dipping units of altered ultramafics that sit below ~20m of overburden including ~10m of pisolitic laterite. These units range from Komatiite to peridotite and have been intensely altered by silica, carbonate and chlorite, with little relic textures visible. Occasional intense fuchsite alteration is also present. Mineralisation is associated with areas of increased shearing, with associated increases in sulphides in quartz veins. Thin zones of black shale are present in areas of high strain. The deposit is crosscut by NW trending faults which seem to both dislocate mineralised trends, as well as act as zones of higher-grade gold concentration.
Majestic
Majestic is hosted in a quartz diorite on the western edge of the Juglah Monzogranite. The quartz diorite is equigranular with up to 10% quartz, intruded by porphyritic dykes bordering the main mineralized zone. A deep weathering profile of 30-40m (up to 60m) covers the deposit, with weak supergene mineralization above 35m beneath a stripped zone. NS, steep west-dipping structures dominate, with two plunges identified: gentle north-south plunge in veins with sulphides showing strong gold grade correlation moderate southwest plunge with silicate-infill veins, shears, and moderate gold grades. Two mineralization styles are noted: biotite-pyrite: linked to porphyritic dykes elevated gold with increased pyrite and biotite brecciation albite-silica-pyrite: high gold and copper with pyrite often in quartz-sulphide veins with albite halos later overprinted by non-mineralized albite-silica. Mineralizing fluids are likely magmatic, with changes due to gradual cooling, and early mineralization overprinted by later veining.
Jones Find
Jones Find comprises a north-striking, steeply west dipping sequence of sheared mafic-intermediate intrusive rock. The host is locally foliated and schistose. Widespread alteration comprises silica-carbonate, whilst localised zones of silica-sericite-kaolinite are observed as well as silica-sericite-chlorite(-biotite). The weathering in the area is typically to depths of 20-35m and displays evidence of supergene enrichment.
Structurally, Jones Find is located on the eastern flank of the south plunging Bulong Anticline. The western margin of the granite to granodiorite phase pluton coincides with a major northwest striking shear (Majestic shear/fault). Jones Find is inferred to lie on a subsidiary splay of this major shear zone. There are several interpreted NE to NNE structures within the area controlling the distribution and strike extent of individual lodes within the mineralisation envelope.
Locally, the granitoid exhibits intense shear related deformation, which is associated with alteration haloes of up to 100m in width. The following styles of gold mineralisation have been recognised at Jones Find: narrow vein gold hosted within quartz veins associated with shearing and biotite/sericite alteration most old workings are developed in these zones quartz-biotite-clay ± albite alteration associated with anomalous gold assays ranging from 0.1g/t Au to 0.4g/t Au supergene enriched gold mineralisation within the saprolitic zone.
Crown (open pit)
Crown is characterised by a lack of topographical relief and is covered by recent alluvium and colluvium up to 4m deep. The area is dominated by altered granodiorite which hosts the mineralisation. To the immediate south of Crown, the mineralisation appears to be truncated by the ENE trending Celebration dyke that forms part of the Widgiemooltha Supersuite.
Alteration over Crown appears to be middle green schist facies regional metamorphism which has generated new assemblages of plagioclase-actinolite-biotite-quartz-clinozoisite-
ilmenite-sphene-chlorite-sulphides (pyrite, chalcopyrite, pyrrhotite). Mineralisation is associated with narrow quartz sulphide veins and sulphide veinlets that trend roughly north south and dip steeply to the west. Mineralised structures are observed at surface.
Fingals Fortune
The Fingals Fortune deposit lies on the western limb of the Mt Monger anticline dipping 30-40° southwest. High-Mg pillow basalts in the footwall are separated from overlying dolerite sills and basalts by bedding-parallel shears hosting mineralization. Three deformation events are identified: bedding-parallel thrusts (340° strike, 30-40° dip) with mineralized quartz veining forming shear zones 1-6m thick sinistral subvertical oblique-slip shear zones (345° strike) that overprint thrusts EW brittle faults (70° strike) between historic pits. Mineralization is controlled by structural reactivation, primarily in sericite-altered felsic porphyry often within quartz veins. Three orientations of mineralization include: moderately west-dipping veins along thrusts flat-lying south-dipping veins along tensional structures possible narrow subvertical veins along oblique-slip zones. Thicker mineralized zones occur where thrusts intersect flat structures.
Fingals East
The Fingals East deposits are situated on the eastern limb of the Mt Monger anticline dipping at ~40-50° to the SE. High-Mg pillow basalts host a coarse-grained magnetic dolerite sill with shearing along the margin and within the dolerite hosting the mineralisation.
Weathering at Fingals East occurs down to depths of 80m through the highly sheared and altered zones. Minor depletion to 10-20m followed by supergene enrichment around 15-24m is present. Bedrock is generally concealed by a mantle of transported to residual red loam up to 2m thick. Reworked lateritic iron oxide pisoliths commonly lie immediately above bedrock.