The Project is situated within the Neoarchaean-Palaeoproterozoic Hamersley Basin and forms part of the West Pilbara Mineral Field.

The Hamersley Group contains five major banded iron formation (BIF) units, of which two, the Marra Mamba Iron Formation and the Brockman Iron Formation, host iron mineralisation, including most of the exploited iron ore deposits in the Pilbara Mineral Province.

There is relatively poor outcrop in the Project area. In the east alluvial/channel iron deposit (CID) cover forms a well preserved Hamersley Surface – i.e. laterite cover, and to the west more Marra Mamba Iron Formation (MMIF) outcrops. From examination of the present NMM drill and gamma logs - and with some confirmation during a limited ground examination during a brief site visit - the full sequence of MMIF appears to be present (i.e. Nammuldi Member to Mt Newman Member, together with some West Angela Member of the overlying Wittenoom Formation (Pearcey & Sergeev 2012, Slater & Kneeshaw 2012). The high grade mineralisation typically occurs within the Mt Newman Member.

Iron mineralisation of the martite-goethite (M-G) type within the Marra Mamba Iron Formation usually occurs preferentially within the Mount Newman Member only. However, enrichment can extend into the MacLeod Member and on occasion into the Nammuldi Member. The in situ ore forming process is a combination of the metasomatic, pseudomorphic replacement of magnetite (resulting in martite - M), the replacement of BIF gangue minerals (chert, silicates and carbonates) by hydrous iron oxides (goethite - G). This can often be followed by leaching which results in the development of limonite (ochreous goethite - oG). Additionally in some areas further alteration of the prime ore can be seen, typically evidenced by secondary goethite along joints / cavities / bedding planes and introduced by late stage percolating groundwaters. Mineralisation boundaries are both conformable with and transgress the stratigraphy, generally thinning down dip.

The majority of mineralisation at Wonmunna is best described as bedded goethite within Marra Mamba BIF. In outcrop, the BIF unit has maintained its primary sedimentary fabric but has been completely altered to intercalated layers of goethite and hematite with some remaining silica rich layers. The mineralisation is primarily the result of supergene iron enrichment.

In addition to bedded mineralisation, several pockets of detrital mineralisation and enriched duricrust occur along the edges of breakaways and in alluvial valleys. This material is comprised of variously mineralised clasts of the Marra Mamba BIF in a matrix of polymictic alluvial/colluvial clays and sand. This mineralisation style is volumetrically small, lower grade and of less commercial interest than the bedded style. There may be potential, however, to beneficiate the lower grade material to produce a higher-grade product. There is no plan to mine and treat any of this BIF resource at this stage.

Wonmunna is an open pit mine used conventional truck and shovel mining method with drill and blast, located 80km north-west of Newman in the Pilbara region, Western Australia.

On 22 March 2021, Mineral Resources Limited announced first iron ore production from Wonmunna Iron Ore Mine.

Acorrding to the Mining Proposal 2015 the planned Wonmunna mining operation is to mine three deposits:
- North Marra Mamba (NMM) (two main pit areas with five pits on the East and one pit on the West of the Weeli Wolli Exclusion Zone),
- Central Marra Mamba (CMM) (one pit) and
- South Marra Mamba (SMM) (two pits).

The provided pits will have the following parameters:
Depth - 50m maximum
Batter height - 20m
Berm width - 5m
Ramp gradient - 1:10
Ramp Width - 25m dual (20m single)
Bench height - 6m
Batter angle - 65
Stack berm width - 5m
Overall wall angle - 45

Wonmunna ore to blend with Iron Valley and the proposed Lamb Creek and Wedge mines creating Utah Point Hub.

Acorrding to the Mining Proposal 2015 Ore will be crushed and screened to a minus 8mm product size. This will be undertaken using a modular crushing and screening facility to process up to 5 Mtpa over the mine life. Mobile dry processing plant will require a low pad of 5m to be built with overburden from pre-stripping of the nearby NMM-west pit. Water will be added in the process and on the stockpile to mitigate dust generation.