The Greenbushes pegmatites belong to the Lithium Caesium-Tantalum family. The Greenbushes pegmatite deposit intrudes along a major northwest regional fault zone. It is approximately 2,525 million years old. The pegmatite consists of a large main zone over 3 kms long and up to 300 m wide with numerous smaller pegmatite dykes and pods flanking the main body. The Greenbushes pegmatites are mineralogically zoned in a lenticular interfingering style along strike and down dip. The lithium zone is over 2 kms long and enriched in the lithium-bearing mineral spodumene which often makes up 50% of the rock. Tantalum. The Greenbushes pegmatite has unique features that distinguish it from many other rare-metal pegmatites.

Lithium ore (spodumene) at Greenbushes is mined from the fresh, unweathered zones in the pegmatite that are exposed in the open pits.

Mining is traditional drill and blast method with ore graded and stockpiled according to its mineralogical characteristics and grade. Waste material is trucked to designated areas within the site where it is contoured and replanted as part of an ongoing rehabilitation plan.

The Greenbushes Lithium Operations has two processing plants, one producing technical-grade lithium concentrates and one producing chemical-grade lithium concentrate. Ore containing Li2O is fed into the processing plants which upgrade the lithium mineral, using gravity, heavy media, flotation and magnetic processes, into a range of lithium concentrates for bulk or bagged shipment.

Various operating modes are used in the processing plants to produce a variety of different lithium concentrates to meet specific customer requirements.