Core Lithium (ASX:CXO) has commenced underground decline development at the BP33 deposit within its Finniss Lithium Operation in the Northern Territory.
The portal cut marks the start of underground development at BP33, following the award of an underground mining services contract to Develop Global (ASX:DVP) in May 2026.
Civil works and box cut remediation have been completed, with ground support for the portal face in place ahead of site handover.
The BP33 deposit is central to the Finniss operation and consists of one large, sub-vertical, mineralised pegmatite, providing a low-cost underground production base with a mine life exceeding 10 years. The deposit remains open at depth.
Underground development will progress in parallel with open pit mining at the Grants deposit, which is expected to deliver approximately 780,000–790,000 tonnes of ore and 130,000–140,000 tonnes of SC5 spodumene.
First development ore from BP33 is expected in mid‑2027, with nameplate production targeted for mid‑2028.
“The portal cut marks a significant milestone for Core and the commencement of underground development at BP33,” Core Lithium Managing Director Paul Brown says.
“Since announcing the Final Investment Decision and funding package in mid‑March, Core has made substantial progress across the Finniss operation.
“In just three months, the Company has awarded all major mining contracts, commenced mining at the Grants open pit, secured two DSO fines sales and the sale of 5,000 tonnes of spodumene concentrate with the first shipment now underway, commenced underground decline development at BP33, and advanced brownfields works at the DMS plant.”
The Finniss logistics chain is now fully operational, with the first shipment of 20,000 tonnes of lithium fines and 5,000 tonnes of stockpiled spodumene concentrate successfully departing from Darwin Port. Payment for the shipment is expected before the end of the June quarter.
Write to JC Villarba at Mining.com.au
Images: Core Lithium



