Japanese researchers find invisible gold in massive quantities hiding beneath seafloor

Japanese researchers discovered black smoker chimneys and hydrothermal mounds that are actively forging vast quantities of gold along the submerged volcanic crater off the southeastern coast of Japan. The hydrothermal vents are not only releasing small particles of gold but are also producing "invisible gold" that cannot be seen with the naked eye or even through a regular microscope.

Instead, the gold is wrapped up inside materials on the seafloor. Scientists reported that the concentration of this hidden gold in the underwater crater is the highest ever recorded worldwide. The discovery was published in the report after an international team of scientists warned that active seafloor mounds need to be protected from commercial mining interests.

The Higashi-Aogashima vents were discovered in 2015 within Japan's exclusive economic zone, and to this day, it remains unknown how much marine life these hydrothermal fields host. Researchers from Shizuoka University, Waseda University, and the University of Tokyo in Japan jointly analysed rock samples from hydrothermal fields located nearly 350 kilometres (217 miles) south of Tokyo.

Japan's hydrothermal vent

Using secondary-ion mass spectrometry (SIMS), a highly sensitive method capable of detecting small amounts of gold, researchers discovered secret deposits of "extremely high-grade" invisible gold. These tiny gold nanoparticles are trapped inside pyrite, a sulfide mineral formed when hot, metal-rich fluids spew from the seafloor. Because of its shiny appearance, pyrite is commonly known as "fool's gold."

The study found that real gold exists within pyrite in two forms: as microscopic nanoparticles and as individual gold atoms embedded within the mineral's crystal structure. Both forms were identified in the Higashi-Aogashima caldera. According to the researchers, the pyrite found in the underwater crater contains the highest concentration of gold ever recorded. The site is also relatively shallow compared with other hydrothermal vent fields in Japan being considered for resource development, making it a promising location for future mining.

Although no commercial gold mine currently operates on the ocean floor, the Higashi-Aogashima caldera's accessibility and exceptionally high gold content have made it a strong candidate for future extraction. Scientists, however, are still working to develop an economical and efficient method to recover this "invisible gold" from seafloor minerals.