Summary:
Laiva is classed as an orogenic gold deposit.
Mineralization comprises sheeted quartz-sulphide vein arrays within multiple, sub-parallel, mylonitic shear zone, hosted in metavolcanic and quartz diorite rocks. Mineralization occurs in two main bodies, the North Pit with Eastern Extention in the north, and the South Pit in the south.
At the North Pit, mineralised shear zones can be traced over a strike length of up to 600m, with the mineralized zone (including the Eastern Extention) occurring over an area of 1300 m by 450 m. In the South Pit area, mineralization occurs over an area of 500 m by 400 m. Mineralization has been intercepted at depths of up to 250 m below surface and is open down pit, apart from the western part of the North Pit where mineralization is truncated by the granite pluton. In both the North and South Pits, the mineralized shear zones vary in windth between <1 m to >10 m.
The mineralised shear zones display distinct structural trends in differetn parts of the deposit, with the orientation being dependent on proximity to the Red Shear Zone. West of the Red Shear Zone, mineralised shear zones strike east-northest and dip steeply (78 degrees to 85 degrees) south-southeast. Immediatly east of the Red Shear Zone, mineralised shear zones strike east-northest and dip steeply west- southwest, transitioning to av almost easterly strike wuth southerly, steep dip progressively to the east.
Within the mineralized shear zones, vein density varies between 1 and 29 veins per meter. Mineralized shear zones display sharp contacts with the host rocks and there is no gold grade associated with the narrow selvedges. In general, veins are more closely spaced in the metavolcanic rocks compared to the veins hosted in quartz diorite, and there is a positive correlation between vein density and gold grade. This increased vein density and gold grade in metavolcanic rocks compared to quartz diorite may be attributed to contrasting arheology and/or chemical composition of the host rocks.
Individual veins are typically planar, narrow (2 to 5 mm, rarely 2-5 cm) and display localized pinching and swelling, although the mineralized structure may be continuous over tens of meters.
Quartz veins are composed of very fine-grained, massive, blue-grey quartz with variable, disseminated and blebby, fine- to medium- grained pyrite, arsenopyrite, pyrrhotite, and chalcopyrite. Molybdenite is rarely observed, mainly in the Eastern Extension mineralization.
Gold grade continuity is variable along strike and down dip. Whilst structural continuity and mineralization is continuous along strike and down dip, elevanted grades of >1 g/t gold display a localizedcharacter. Higher grades of >5 g/t gold are relatively common but generally dispersed within a mineralized structure.