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Chinese expedition assays seabed sulfide mounds at up to 15.4 grams of gold a tonne
The preliminary numbers from an 18-day cruise inside China's exclusive economic zone are peak grades off three sulfide mounds. No tonnage was published, so a metals buyer has nothing to put in a cost model.
The Product Desk · Product desk
What happened
- Researchers from Tsinghua University, the Qingdao Institute of Marine Geology and Shanghai Jiao Tong University spent 18 days surveying a western Pacific hydrothermal field.
- In a back-arc basin they identified three large cone-shaped sulfide mounds formed by high-temperature, mineral-rich fluids venting through the ocean floor.
- Preliminary analysis put gold at up to 0.45 troy ounces per US short ton of ore and silver at a maximum of 36.3 troy ounces per short ton.
- The work was done from the Xiang Yang Hong 10, which left Shenzhen on August 10 and supported seven deep-submergence dives during the mission.
- Precise coordinates have not been disclosed. Chinese state media placed the site inside the country's exclusive economic zone.
Compiled by The Product DeskSomething wrong?How this is made
Why it matters
- constraint A peak grade needs a tonnage behind it before it becomes tonnes of contained copper, zinc, gold or silver. Without one, no purchasing team can build a cost or hedging case on these figures.
- decision The assay makes a fundable case for more dives. It makes no case for ordering seabed cutting equipment, and the researchers themselves flag the extraction as technically difficult and environmentally challenging.
- exposure Outside geologists cannot tie the grades to a place on the seabed on their own; the only independent locator so far is commercial vessel-tracking that put the ship north and east of Taiwan.
- precedent Hydrothermal fields run from the Kuril Islands toward waters northeast of New Zealand. Other coastal states have the same formations to survey inside their own waters.
A buyer who tries to put 0.45 troy ounces a short ton into a supply model gets stuck on the second line. Contained metal is grade times tonnage times recovery. The expedition has reported a grade [3].
In the units a resource statement uses, that gold figure is 15.4 grams per tonne, and the silver figure of 36.3 troy ounces a short ton is about 1,245 grams per tonne [13][14]. The researchers reported precious-metal concentrations significantly higher than those typically found in terrestrial deposits, the South China Morning Post reported [10].
Both figures are ceilings from a preliminary analysis of three cone-shaped mounds [3][2]. A maximum tells you what the best sample assayed. A model needs the average across the deposit and a tonnage. The team published neither.
The ore is mostly chalcopyrite, pyrite and sphalerite [9]. Those are copper, iron and zinc minerals, so any eventual output is base metal with the gold and silver alongside it.
Song Shiji, vice-dean of the Institute for Ocean Engineering at Tsinghua University and one of the project's lead scientists, said the newly identified seabed area could have substantial economic value [8]. The same account has the researchers noting that extracting minerals from the deep seabed remains technically difficult and environmentally challenging [11].
More than a dozen earlier surveys of the region found dozens of high-temperature vents at depths between 2,300 and 4,920 feet, with fluid temperatures above 599 degrees Fahrenheit [5]. In metric that is 700 to 1,500 metres and 315 C [15][16], round numbers that show which way the conversion ran before the figures reached English-language readers.
An average grade across the deposit, tonnage, recovery from a tool that works at that depth, and permission to work the site: those are what turn a seabed assay into something a procurement plan can use. The expedition has reported one of them, as a maximum.
What to watch
- An average grade across the three mounds and a tonnage estimate published in a peer-reviewed paper.
- Coordinates, a lease application, or any filing that names the site.
- A follow-up cruise carrying extraction hardware instead of sampling gear.