Summary:
The Razorback Iron Project covers sedimentary lithologies of the Adelaide Geosyncline, a linear north-south to north-east trending tectonic rift basin comprising sediments deposited during the late Proterozoic and early Cambrian Eras. The host rock to the magnetite at the Razorback Iron Project Neoproterozoic glaciogenic meta-sediment of the Braemar Iron Formation.
The mineralisation within the Braemar Iron Formation forms a simple dipping tabular body with only minor faulting, folding and intrusives. Grades, thickness, dip, and outcropping geometry remain very consistent over kilometres of strike. While the bedded magnetite has the highest in-situ iron content, typically 19-35% Fe, the tillitic unit, at typically 15-26% Fe is diluted by the inclusion of lithic fragments, such as iron-poor granite and metasedimentary dropstones.
Razorback Ridge iron deposit is positioned on the north dipping (approximately 40° to 60°) limb of the Pualco Anticline. Whitten (1970) divided the Braemar Iron Formation at Razorback into seven sedimentary packages, comprising members A to G, with a total thickness ranging from 480m to 780m. Of these, members A, B, D and G are of economic interest and all outcrop or sub-crop at the surface, with member B forming the prominent ridge.
The two main facies types that make up the ore horizons at Razorback Project are: 1) tillitic / diamictitic ironstone and 2) laminated / bedded ironstone with mineralisation stratiform in nature. While macroscopically, the two facies are quite different, compositionally the iron-rich components are very similar.
The ironstones are typically fine grained (less than 0.05 mm) and are composed of magnetite, hematite and quartz, with lesser amounts of sericite, chlorite, dolomite, feldspar and apatite. The non-ferruginous bands within the bedded / interlaminated siltstone consist of quartz, biotite, dolomite, plagioclase, sericite and chlorite, with minor amounts of both hematite and magnetite. Laminated ironstones often have well defined laminae, varying in thickness from < 0.5 mm to 50 mm, with the iron rich bands containing between 20% - 80% magnetite and hematite.
On 9 February 2023, Magnetite Mines announced that the Iron Peak deposit Mineral Resource Estimate, part of the wider Razorback Iron Ore Project.
The magnetite host rock at Razorback and Iron Peak occurs as either tillitic or bedded siltstone. The bedded or laminated ore is dense dark blue and can show sedimentary features such as cross bedding and slumping. The Geology of the Iron Peak Prospect is an extension of the geology at Razorback as following the consistent lateral continuity of the Braemar Iron Formation. For this reason there are no deviations to the methodologies/procedures utilised towards drilling and sampling between the two prospects.
The magnetite occurs as 10 to 150 micron euhedra in layers up to 500 micron thick, and can form up to 80% of the rock. Haematite can occur associated with crosscutting right angle cleavage, related to later deformation.
The tillitic ore is medium to dark grey, massive and contains erratics from 10mm to 1m in diameter. The fragments are typically metasediments, metavolcanics and granites. The magnetite is similar to that seen in the bedded ore type. Haematite occurs, but is irregularly distributed through the rock.
Dimensions
Razorback and Iron Peak extend approximately 7 km and 3km along strike respectively, with a maximum depth extent from outcrop at surface to approximately 320m below surface and typical total thicknesses of 100 m to 150 m.
Commodity Production
The Razorback Project will produce a high-grade magnetite concentrate with 67.5%-68.5% Fe concentrate grades.
The revenue assumption assumes a US$41/t premium applied to the 10-year, real, average 62%Fe price of US$115/t, as reported by Magnetite Mines Ltd.
Operating costs and pre-production capital costs are shown as average values of the ranges provided by Magnetite Mines Ltd.
| Commodity | Product | Units | Avg. Annual | LOM |
|
Iron (magnetite)
|
Concentrate
|
kt
| 5,000 | 331,000 |