The Mt. Cattlin Project lies within the Ravensthorpe Terrane, with host rocks comprising both the Annabelle Volcanics to the west, and the Manyutup Tonalite to the east. The contact between these rock types extends through the Project area.

The Annabelle Volcanics at Mt. Cattlin consist of intermediate to mafic volcanic rocks, comprising both pyroclastic material and lavas.

Both the Annabelle Volcanics and the Manyutup Tonalite are intruded by numerous fine to coarse-grained metamorphosed dolerite dykes. A NNW trending gabbro (termed pyroxenite in earlier reports) occurs at the eastern edge of the Mt. Cattlin pegmatite ore body.

The pegmatites which comprise the ore body occur as a series of sub-horizontal dykes, hosted by both volcanic and intrusive rocks. Several dolerite or quartz gabbro dykes trending roughly ENE and north-south cut all lithologies including the pegmatite dykes and are believed to be Proterozoic in age.

Mineralisation.
Lithium and tantalum mineralisation occurs in pegmatites, which have intruded both the Annabelle Volcanics and the Manyutup Tonalite, close to the contact between these two sequences.

The pegmatite dykes occur as a series of sub horizontal to gently-dipping horizons. In places they occur as stacked horizons which overlap in section. Pegmatite mineralisation defined to date covers an area of around 1.6 km east-west and 1 km north-south. The main pegmatite units drilled to date generally lie between 30 m and 60 m below the surface, and outcrop in some locations. However, deeper zones of lithium-mineralised pegmatites occur over 140 m below the surface to the northwest of the main ore body and may have potential to be mined from underground.

The pegmatites have a diverse mineralogy with major minerals comprising quartz, albite, cleavelandite (platy albite), microcline, perthite, spodumene, muscovite and lepidolite. Minor minerals include tourmaline, schorlite, elbaite, beryl, microlite, columbite-tantalite, sphalerite, amblygonite-montebrasite, triphylite, apatite, spessartite and fluorite. Spodumene is the predominant lithium ore mineral, and several types of spodumene are recognised, including light green and white varieties. Tantalum occurs as the manganese-rich end members of the columbite-tantalite series including Ta-rich manganotantalite, and as microlite.

The lithium minerals within the pegmatites are shown below:
- Spodumene LiAl(SiO3)2 contains 4 to 8 % lithium oxide (lithia).
- Amblygonite, LiAl(F,OH)PO4, contains 8 to 10 % lithia.
- Lepidolite, (lithium mica) contains 2 to 4 % lithia.
- Cookeite, (lithium chlorite).

The mineralogy of the pegmatites varies laterally, and can also be crudely zoned in a sub-vertical manner (perpendicular to margins), with zones differentiated by mineralogy and grain size.

Part of the northeast of the deposit contains the lithium-bearing mica lepidolite, which does not occur in the rest of the deposit. The lepidolite-rich zones contain higher tantalum (mainly microlite) grades. Zones include an aplitic rock comprising mainly quartzalbite- muscovite near contacts with country rocks, and zones of predominantly light green, and predominantly white spodumene. Lepidolite is generally associated with the white spodumene. Quartz-tourmaline veins are associated with the pegmatites and occur in places in the country rocks up to 10s of metres away from the pegmatites.

The Mt Cattlin mine operations include open-pit mining of a flat-lying pegmatite ore body. The flat-lying nature of the ore body allows mining to proceed at a reasonably constant strip ratio once the ore is uncovered. Mining is carried out using excavator and truck operations, delivering to a conventional crushing and Dense Media Separation (“DMS”) gravity recovery circuit. Contract mining is used for grade control drilling and earthmoving operations (drilling, blasting, load, haul and ancillary work) for the open-cut mining operation.

The crushing plant consists of a 3-stage crushing circuit producing a -6mm product from ROM ore at a treatment rate of 1.8 million tonnes per annum.

The concentrator consists of reflux classifier, dual size steam, two stages of DMS cyclones, with mechanical attritioning of the intermediate sink product. Recent additions include an ultra-fines DMS circuit, a secondary float re-crush circuit and several optical sorting units. The final spodumene concentrate is trucked to the Esperance port for export.