Pilgangoora is already one of the world's largest lithium-tantalum deposits, and continued exploration success look set to add to what is already decades of resources to extract.

Recent exploration drilling has turned up encouraging new zones of thick near surface pegmatite mineralisation at West End and Monster North outside current resources.

In addition, high-grade thick intercepts have been returned from the north extension of the Central Pit in recent drilling.

Results to date include 20m at 1.62% lithium oxide from the north extension of Central area and 22m grading 1.15% lithium oxide from 10m in a new pegmatite sheet at Monster.

Other intercepts include 12m at 1.99% lithium oxide from 184m and 97 parts per million tantalum oxide.

Lithium and tantalum grades tend to increase in the north of the system, and recent drilling has returned tantalum oxide grades between 99-175ppm, with the tantalum credits capable of reducing production costs by around 20%.

Further assays are coming, as is more drilling to shift inferred resources to the indicated and measured category to support the basis of an expanded resource and reserve estimation for the Stage 2 expansion project to at least 5 million tonnes early next year.

The strike at Pilgangoora already expands over the best part of 10km, from the proposed Lynas Find pit in the north to the South End pit in the south, with around half of the known 156Mt at 1.25% lithium oxide resource is in the Central area.

Pilbara managing director Ken Brinsden describes Pilgangoora as a massive geological system already, but one that is still emerging because regional exploration is at a fairly early stage as the pegmatites were known about for years, but were never a focus for past explorers.

It wasn't until Pilbara's founders were walking the tenement after its acquisition from Global Advanced Metals when they noticed the out-cropping veins of spodumene and decided to assay for that mineral while drilling to support a tantalum development.

It returned some astonishing grades that, while not the equal of the Greenbushes mine in the South-West region, demanded attention, particularly as the global demand for lithium was heating up.

Drilling to date, including grade control, infill and exploration tests, all continue to pleasantly surprise.

With the recent drilling at Central North and Monster North, and with ore grade intercepts in the Central area as deep as 300m, Brinsden has no doubts the system will continue to grow.

At stage 2's 5Mtpa production there is enough product for around 20 years, but Brinsden said there was no reason why the operation can't evolve with a market he can't see being swamped by oversupply.

Pilbara is also champing at the bit to get on with exploration at its Mt Francisco project with Atlas Iron.

Mt Francisco is the largest mapped pegmatite swarm in the Pilbara, and while the company had hoped to be drilling this year, however the process for access to the project area has taken longer than expected.

It now has the consents from the Kariyarra native title claimant group and the Mugarinya Community Association, and is hopeful of gaining its entry permit from the Aboriginal Lands Trust in December.

Field mapping and access track redevelopment is planned in early 2018.

This will be followed up by detailed sampling and targeted drilling.

Brinsden was hopeful that Mt Francisco, which is 50km from Pilgangoora, would develop into a project large enough to support its own plant.

Haydn Black travelled to Pilgangoora as a guest of Pilbara Minerals.