First Japanese diamond unearthed

A natural diamond has been discovered in Japan for the first time, in volcanic rock in Ehime Prefecture by a research team from Nagoya University, it was announced Monday.

The team, whose members include researcher Tomoyuki Mizukami, said at a meeting of the Geological Society of Japan in Sapporo that the find goes against an established theory that a country like Japan, with active geological movements, does not produce diamonds in a natural environment.

However, because the discovered diamond's size is only about one part per thousand millimeters, it cannot be observed even using a microscope.

To protect the extraction site, the team has refused to disclose its exact location, but it is somewhere in the city of Shikokuchuo. The researchers say the site has no prospect of commercial production of diamonds.

The group collected the volcanic rock, which lay exposed on the ground, and radiated a laser beam on a "frothy" spot on it. It detected a wavelength that is characteristic of a diamond, and estimated its size.

A frothy spot is caused when a mineral is formed in the ground by trapping carbon dioxide, but the group said it remains unknown if it has something to do with the creation of a diamond.

A natural diamond is thought to be produced inside high-temperature, high-pressure conditions at depths of more than 100 km below ground.

"We'd like to search for a mechanism that explains how the rock got elevated from the deep part of the Earth," the team said.