The lithium train shows no sign of slowing in WA as the state's newest mine officially opens, with plans already in motion to expand the Pilbara operation.

The first shipment from Pilbara Minerals’ Pilgangoora lithium-tantalum project left the mine on October 2 but was officially opened by WA Mines and Petroleum Minister Bill Johnston on Friday.

Pilbara Minerals' Pilgangoora lithium mine.

Located 120 kilometres south of Port Hedland, the mine will produce 330,000 tonnes of lithium a year and about 300,000 pounds of tantalum.

The Pilgangoora project’s workforce peaked at more than 800 during construction, but now there are about 200 operational staff on-site and in Perth.