Summary

Mine Type	Underground
Study Completed	Feasibility
Status	Inactive / Suspended
Commodities	Gold
Mining Method	Sub-level open stoping (SLOS) Overhand Cut & Fill Mechanized Cut & Fill
Backfill type	...
Mine Life	...
Snapshot	Blue Spec is one of several Calidus expansion plans for Warrawoona mine. Blue Spec is a steeply dipping vertical/sub-vertical narrow vein deposit. There are two separate mining areas located ~1.2 km apart along strike, named Blue Spec and Gold Spec. The Sulphide Plant would be constructed at Warrawoona with Blue Spec and Copenhagen ore trucked to Warrawoona for processing. Blue Spec numbers are based on the feasibility study released 29 September 2022 and inflated 5%. On 11 September 2023, Calidus Resources announced the final approval had been received to commence mining the Blue Spec project. Hayden White and Daniel Woodhouse of FTI Consulting were appointed as Deed Administrators of Calidus Resources Limited and its subsidiaries on 9 October 2024. In January 2025, all Calidus shares were transferred for nil consideration to the DOCA proponent’s nominee. As of October 2025, there is no new information about the mine.

Deposit type

• Orogenic
• Vein / narrow vein

Summary:

The Blue Spec gold project lies within the Mosquito Creek Formation, a thick sequence of siliciclastic metasediments comprising dominantly quartz-rich arenites and shales that has undergone multiple periods of deformation. The Mosquito Creek Formation is located within the extensive rhombic Mosquito Creek Basin in the southeastern extent of the Pilbara granite-greenstone terrane (Easterday et al., 2008). The Mosquito Creek Formation is interpreted to be Mesoarchaean in age (Bagas et al., 2008).

Stratigraphy within the basin generally trends east–northeast, with both northwest and north–south trending regional fault orientations exerting major influences on the basin architecture. Intrusive dykes comprising dolerite and hornblende-bearing tonalities are also observed within the basin, while gabbroic sills are a prominent feature along the northern and southern margins of the basin. The Blue Spec line is a clearly defined and mapped, major fault structure that nucleated during north–south oriented regional shortening, upright folding and thrusting along a major anticlinal hinge position. It has undergone multiple periods of deformation (Easterday et al., 2008).

The Blue Spec Shear gold-antimony deposits are interpreted to be epizonal orogenic gold deposits. Gold mineralisation is associated with the Blue Spec Shear Zone that was emplaced during two deformation events. The first event produced a laminated quartz-carbonate vein with minor pyrite, gold and arsenic. The second event overprinted the first with brecciated and recrystallised quartz-carbonate veins containing pyrite, gold and localised concentrations of massive stibnite.

The Blue Spec Shear Zone runs east–west, and can reach 30 m in true thickness. Localised narrow shear splays have been observed bifurcating from the main zone in historically mined void models. Mineralised lodes are steeply dipping, with primary mineralisation located in dilatant jogs in the shear zone.

Dimensions
Mineralisation domains in Blue Spec (seven domains in total, five with low-grade halo sub-domains) extend over a 350 m strike length. Lode widths are highly variable and range from 0.5 m to 4 m. The Mineral Resource extends 885 m from the surface (365 mRL) to a lower limit of -520 mRL. The mineralisation domain in Gold Spec (one domain with a low-grade halo sub-domain) extends over a 480 m strike length. Lode widths are highly variable and range from 0.3 m to 11 m. The Mineral Resource extends 450 m from the surface (370 mRL) to a lower limit of -80 mRL. Mineralisation within the model which did not satisfy the classification criteria for Mineral Resources remained unclassified.

Mining Methods

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Comminution

Crushers and Mills

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Processing

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Commodity Production

Operational metrics

Metrics
Annual processing rate	....