The Mt Marion lithium mineralisation is hosted within a number of sub-parallel, northeast to northwest trending pegmatite intrusive bodies which dip at between 10° and 30° to the west. Individual pegmatites vary in strike length from approximately 300 m to 1,500 m and average 15 m to 20 m in thickness, but vary locally from less than 2 m to up to 35 m thick. The pegmatites are currently defined to a depth of up to 250 m below surface, with the feeder zone extending down to a depth of 400 m below surface.

To the southwest of Area 2W, large intervals of spodumene-bearing pegmatite intersected during the 2016 drilling are interpreted to be part of a sub- vertical, northeast striking feeder zone. The feeder zone is interpreted to be around 40 m to 80 m wide, extending approximately 400 m along strike and down to over 500 m below surface, and is open at depth.

The lithium occurs as 5 cm to 30 cm long greywhite spodumene crystals within medium grained pegmatites comprising primarily of quartz, feldspar, spodumene and muscovite. The spodumene crystals are broadly oriented orthogonal to the pegmatite contacts. Some zoning of the pegmatites parallel to the contacts is observed, with higher concentrations of spodumene occurring close to the upper contact.

Mining of the deposit is via conventional drill and blast open cut mining methods.

Ore is processed on site to produce spodumene concentrates.

The Mt Marion Upgrade Project involves the design and construction of a new plant circuit that will convert the current 4% coarse product stream into a 6% flotation product. CSI Construction is significantly advanced in this project with commissioning scheduled for the first half of FY19.