Summary:
The Iron Ridge is a northwest trending Archaean aged granite greenstone terrain of the Yilgarn Craton. It is a marked physiographic feature, 3-5km wide, 40km long, within which there is good exposure of metabasalts showing mainly doleritic and minor basaltic and gabbroic textures. Such exposures occur between ridges defined by weathered, steeply dipping beds of banded iron-formation which form less than 10% of the thickness of the sequence.
The Iron Ridge Project contains one main BIF horizon which exhibits significant iron enrichment in two locations (Wilgie Mia and Little Wilgie Mia). The mineralisation comprises a mixture of banded hematite (specular and earthy, goethite and shaly limonite iron ore. It has been documented that the primary ore mineral is martite. The ore lenses have formed by remobilization of iron and replacement of jaspilites (BIF) during deep-seated thermal metamorphism. Subsequent supergene oxidation, leaching and hydration of the iron ore has resulted in the formation of goethite and the concentration of secondary hematite (occasionally in the form of red ochre).
Three parallel to sub-parallel ranges of BIF occur on the tenement. The Main BIF (mapped as hematite) is approximately 50m wide, with much thinner (several metres) BIF ridges to the south (designated Little BIF 1 and 2 respectively). Little BIF 1 and 2 are defined by discontinuous goethitic outcrops at a lower elevation than the Main BIF.
The Iron Ridge deposit constitutes two major, parallel BIF units, separated by a range of 14–36 m, which outcrop for ~75% of the drilled strike length of 600 m. The interpreted area lies in a minimum bounding rectangle of 7,019,245 mN, 567,498 mE to 7,019,663 mN, 7,019,605 mE in MGA Zone 50 coordinates.
The sharp contacts to the dolerite are visible in the outcrop and in drilling, forming lateral widths of 31 m for BIF 1 and 6 m for BIF 2, which are consistent for the interpreted depth. The depth of the north-eastern extent of BIF 1 reaches an RL of 247 m for 280 m vertical depth, while the south-western extent reaches an RL of 247 m for 280 m vertical depth. The depth of the north- eastern extent of BIF 2 reaches an RL of 341 m for 176 m vertical depth, while the south-western extent reaches an RL of 510 m for 44 m vertical depth.