Tonga Offshore Mining, the wholly-owned subsidiary of Nautilus Minerals, has upgraded mineral resource estimates for its underwater polymetallic nodule mining project in the eastern Pacific, off the coast of Mexico.
The Clarion-Clipperton fracture zone (CCZ) project's inferred mineral resource is estimated to have increased from 410 million tonnes to 685 million tonnes.
The latest figures include portions in the inferred, indicated and measured categories after completing exploration campaigns in the Central Pacific area in 2013 and late 2015.
Nautilus Minerals CEO Mike Johnston said: "Technological advances in mining, oil, gas and maritime technologies over the last 20 years now mean there are reasonable prospects for economic extraction of these massive mineralised systems.
"At Nautilus, we are both excited and privileged to be leading the development of this significant, currently untapped potential, first with our high grade Solwara 1 Seafloor Massive Sulphide (SMS) project, and other SMS systems in the South West Pacific, and now with this updated polymetallic nodule mineral resource in the CCZ."
Nautilus said that the mineral resource estimate at a cut-off of six wet kg / m² is the selected base case scenario considering a non-selective bulk mining operation.
Nautilus was granted the first mining lease for polymetallic seafloor massive sulphide deposits at the prospect known as Solwara 1 in the territorial waters of Papua New Guinea.
The company aims to produce copper, gold and silver from the project.
Solwara 1 is expected to commence operations in the first half of 2018 subject to project financing and completion of the company's seafloor production equipment and vessel.