Thunderbird is the first significant mineral sand deposit to be discovered in the Phanerozoic Canning Basin, and is one of the largest and highest grade mineral sands deposits globally, including those currently in production. The Thunderbird deposit formed during an Early Cretaceous marine regression and is hosted by highly weathered Broome Sandstone.

Mineralisation occurs as a thick, broad sheet like body striking northwest, extending from surface to a maximum known depth of 155m over an area at least 11km by 7km. These extents have not been closed off with mineralisation remaining open to the north, south and west. The average depth to top of the main body of mineralisation is 24m and the average mineralised thickness 45m. The deposit is flatlying along the north-eastern flank, but with a dip steepening to 4°along the south-western flank.

Enclosed within the Thunderbird formation is a continuous, very-high grade heavy minerals (>7.5%) zone named the “GT Zone”. This zone is up to 43m thick (average 15m) over an area at least 9km by 7km, strikes approximately north-south, follows the dip of the Thunderbird formation and is open along strike to the south and north.

Thunderbird is a typical dry-mining mineral sand operation whereby a moving void extracts the valuable mineral sands, with waste materials returned to the void enabling progressive rehabilitation of the mined area. Topsoil and overburden are excavated and transported using truck and excavator. Ore is excavated, screened, slurried and then pumped to a nearby wet concentration plant. Retaining cells are constructed in the developed mine void for the return of process tails. Topsoil is returned in a continuous rehabilitation process. As the mining void is established, increasing amounts of overburden are mined and directly returned to the mining void as backfill.

Conventional open pit bulk dry mining techniques have been chosen for ore mining, incorporating dozer traps and in-pit feed preparation units (“Mining Unit Plant” or “MUP”). Initially one MUP is scheduled, with an additional MUP scheduled from year five of operations. The selected mining method is considered appropriate and has been trialled through the full thickness of the orebody by two trial mining programs in late 2020 and mid-2021 and is suited to the large, relatively thick and sheet-like characteristics of the orebody. Minimal pre-strip is required to access the orebody with topsoil and overburden being excavated, hauled and stockpiled using conventional earthmoving equipment. Following mining and feed preparation, the ore will be slurried and pumped to a nearby wet concentration plant (WCP).