The overall resource is up by 60% to 57.3 million tonnes at 1.12% lithium oxide and 117 parts per million tantalum pentoxide for 601,200 tonnes of contained lithium and 13 million pounds of tantalum, using a 0.2% lithium oxide cut-off.

The high-grade resource, using a 1% cut-off, jumped by 56% to 34.9Mt at 1.42% lithium oxide.

High-grade measured resources are up by 136% to 5.7Mt, while measured and indicated resources rose by 27% to 20.7Mt.

The company said the resource made Arcadia Africa’s largest JORC lithium resource, as well as the fourth-largest hard rock lithium project listed on the ASX, and fifth-largest globally.

Prospect only started exploration at Arcadia in mid-2016, and has completed more than 16,000m of reverse circulation and diamond drilling.

“This result is a significant one for Prospect as it confirms the global scale and importantly boosts our confidence and understanding of the Arcadia deposit,” Prospect chairman Hugh Warner said.

“This upgrade provides our PFS team with a robust, high confidence block model and mineral resource estimate to move Arcadia forward to a production decision, which forms part of the ongoing PFS.”

The PFS is due to be completed within weeks.

The December scoping study, which was based on the previous high-grade resource of 23.4Mt at 1.42% lithium, outlined an open pit operation with an expected strip ratio of 2.98:1.

Based on the previous resource, Prospect expected Arcadia to have a mine life of at least 12-25 years.

There are assays from 2017 drilling that didn’t make the cut-off for the new estimate, with mineralisation intersected over 3.5km and the current resource only covering 2km.

Prospect ended 2016 with $A13.3 million in cash after raising $17 million in the September quarter.

The bulk of the funds were raised at 1.4c. Prospect shares last traded at 2.4c after a 9% jump yesterday.