Summary:
The Blacksmith Project is situated within the Hamersley Province which covers an area of approximately 80,000km2 and comprises Late Archaean to Palaeo-Proterozoic rocks of the Mount Bruce Supergroup, which consists of the Fortescue, Hamersley, and Turee Creek groups, overlain by remnants of the Wyloo Group.
The banded iron formation (BIF) units of the Hamersley Group host the bedded iron deposits of the Pilbara with mineralisation occurring predominantly within the Marra Mamba Iron Formation and Brockman Iron Formation. Substantial mineralisation also occurs in overlying detrital units.
At Blacksmith the Brockman Iron Formation is present as either an unenriched BIF or as martitegoethite mineralisation within the Dales Gorge Member, although predominantly as a heavily hard capped goethite-rich style of mineralisation.
The Blacksmith mining lease includes seven deposits: Ajax, Badger, Blackjack, Champion, Delta, Eagle and Paragon. The PFS only considers the development of four deposits - Delta, Paragon, Blackjack and Champion.
Delta geology
Delta is approximately 4km long and 2km wide and includes a number of minor valleys separated by ridgelines which report to a single large valley entrance. The depth of the valley from the floor to the basement contact varies from approximately 20m to 50m on average across the central part of Delta. In the central part of the deposit, overburden (SZ and HMZ) averages 20m in depth and overlies LZ and PZ which can each be up to 30m thick. Within the fingers of Delta, the valley walls are characterised by outcropping lenses of canga overlaying the mineralised Dales Gorge Member with minimal waste overburden. A cross-section is provided in Figure 3.
Paragon geology
Paragon is located in the northeast of the Blacksmith Project and comprises a northern valley containing a deepening detrital sequence north to the lease boundary, and a small, enclosed valley to the south, each separated by outcropping Brockman Iron Formation. The resource is relatively flat lying to shallow dipping of average thickness 5m to 25m in both outcrop and under shallow cover. The valley to the south varies from 16m to 26m deep from the valley floor to top of bedrock and contains a substantial accumulation of canga overlying hardcapped Dales Gorge Member, overlain by lenses of LZ and PZ of varying thickness.
Champion geology
Detrital mineralisation at Champion is predominantly PZ which occurs distal to outcrop, with zones of LZ close to outcrop. Areas of canga overlie hardcap mineralised Dales Gorge Member, and minor channel-iron deposit occurs in the far northwest of the deposit. Canga occurs throughout the Champion deposit as discrete lenses directly on top of hardcap. It tends to predominate along the channel margins where it can assume thicknesses of up to 20m. It becomes more dominant in the northern, narrowest part of the valley where it occurs as lenses up to 15m thick on both sides of the valley. In addition, substantial canga occurs in the western part of Champion. In the northern part of Champion, mineralisation is restricted to the central and western sides of the valley, with the eastern half being almost barren apart from thin lenses of LZ overlying thin canga. In the central part of the valley abutting the CID, the PZ is up to 30m thick.
Blackjack geology
The detrital valley in Blackjack is shallower (up to 60m deep) and narrower than in Champion and Delta. Consequently, no major deposition of HMZ has occurred. Similarly, no CzD2 or CID was identified. The Blackjack valley comprises a thin SZ overlying a simple “layer cake” sequence of LZ and PZ, in approximate 50:50 proportions. A continuous lens of canga occurs to the east. This may grade into PZ along strike towards the centre of the valley. Small lenses of canga occasionally occur at the base of the detrital valley but these have no continuity. Hardcap mineralisation has formed in the Dales Gorge Member in the west as well as to the east in the southern part of the deposit.