The Mount Webber Project consists of three deposits:
• Gibson/Daltons – one deposit split on a tenement boundary;
• Fender – located to the southwest on the same banded iron formation (BIF) unit as Gibson/Daltons; and
• Ibanez – located slightly to the west of Gibson on a parallel BIF outcrop.

The Project is located within the Archaean age Granite greenstone terrane of the Pilbara Craton, with the deposits occurring within the Gorge Creek and Sulphur Springs Groups of the Pilbara Supergroup (Slomp, 2017). Complex folding and faulting have resulted from the deposits being located between two large granitoid complexes – the Shaw Granitoid Complex to the east and the Yule Granitoid Complex to the west (Hermawan, 2013).

The deposits are hosted within the Pincunah Banded Iron Member (Hickman, 2013) of the Kangaroo Caves Formation. The Pincunah Banded Iron Member comprises red-black BIF, chert, tuff, siltstone and shale and is unconformably underlain by the Warrawoona Group mafic and ultramafic lithologies. The BIF and chert of the Pincunah Banded Iron Member form steep-sided ridges with flat-topped summits. The Pincunah Banded Iron Member has been informally divided into Upper and Lower BIF units separated by a thin chert unit.

One dolerite intrusive has been identified in the Fender deposit that cuts the entire sequence, but this has had no apparent effect on the mineralisation.

Mineralisation
The mineralisation has been recorded as predominantly gœthite with minor hæmatite (Hermawan, 2013). The mineralisation occurs as lenses of varying sizes ranging from 10 m to 15 m wide to several hundred metres wide and over a kilometre long and occurs in both the Upper and Lower BIF units, although the majority is within the Upper BIF unit. The mineralisation in the Lower BIF unit is thought to be poddy and laterally inconsistent, and consequently of lower prospectivity. The mineralisation has a hard cap that varies from 10 m to 30 m in depth.

It is believed by Atlas that the mineralisation was formed by supergene processes only. This is borne out by the grade and distribution of the bulk of the mineralisation. However, a brief review of the chemistry of Gibson/Daltons revealed the presence of mineralisation that may have a different origin.

The overall iron grade for the Gibson/Daltons resource (all categories) has been quoted as 57.9% Fe, 0.09% P and 8.3% LOI.

The majority of the holes were between 40 m and 80 m deep, with several extending below 100 m. The deepest hole recorded was 120 m.

A review of the Ibanez database revealed shallower holes, the majority ranging between 30 m and 60 m deep with several deeper than 100 m. The bulk of the mineralisation was goethitic, with minimal hæmatite. A few holes intersected higher grades, e.g. MWRC0933 which averaged 63.3% Fe, 0.094% P and 5.79% LOI for the 36 m intersection between 22 m and 58 m. This is most likely a martite-gœthite rather than having a metamorphic origin.

The mineralisation occurs in synclinal fold closures where the BIF is thickened by intraformational folding, with the synclines corresponding to the topographic highs and the valleys to eroded antiformal hinges.

The mining approach to the Mount Webber deposit is by conventional open pit mining methods using drill and blast methods. Mined material is mined in 6 m-high benches. The blasted rock is loaded across two 3 m-high flitches by backhoe excavators into rigid body trucks.

The contractor provides the mining and processing equipment, completes operations and maintenance activities. The mining of ore at Mt Webber is contracted to BGC Contracting Pty Ltd (now NRW Contracting Pty Ltd).

Stage 1 mining at Mt Webber began in July 2014 at a rate of 3 Mtpa. In late 2014 mining increased to 6 Mtpa following completion of Stage 2 developments. Production increased to approximately 9 Mtpa beginning in August 2017. Mining was reduced back to 7.8 Mtpa between November 2017 to February 2018 before increasing again to approximately 9 Mtpa thereafter. As at August 2020 the Mt Webber mine life is estimated to be 2.5 years depending on future mine plans and ultimate production rates.

Ore and waste is differentiated through grade control practices and ore is trucked to the run-of mine (ROM) stockpile. Ore is segregated into grade categories, namely:
• H0 - +60% Fe
• H1 – 57.5 to 60% Fe
• H2 – 55 to 57.5% Fe (Ibanez and Fender)
• H2 – 53.5 to 57.5% Fe (Gibson/Daltons)
• H3 – 53.5 to 55% Fe (Ibanez and Fender)
• H3 – 50 to 53.5% Fe (Gibson/Daltons).

Material is classified as waste when the grade is below 53.5% Fe for Ibanez and Fender and below 50% Fe for Gibson/Daltons.

The LOM strip ratio is 1 : 0.32 (ore t : waste t).

The Mt Webber is mining at a rate of approximately 9 mtpa. Approximately 7 mtpa of ore is crushed on site. The remaining tonnes are transported by road to the Mount Dove processing facility for crushing.

The processing plant at the Mount Webber site was commissioned with a capacity of 6.0 Mt per year and it regularly achieves levels of 7.0 Mt per year.

The ROM ore is fed into a primary crusher and then through one of two circuits to produce Lump or Fines material in a crushed cone.

The Mount Dove crushing facility has been used to process approximately 2.0Mt per year of Mount Webber run-of-mine ore.