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Natural diamond discovered in Japan. Maybe more in other places if looked for closely

9, 28. 2007

   Natural diamond has been discovered in volcanic rock collected in a mountainous area in Ehime Prefecture. This was reported by a joint research team of Nagoya and Tokyo universities at a meeting held by the Geological Society of Japan in Sapporo, Hokkaido, on Sept. 10, 2007. It was an epoch-making report in respect that it ran counter to a generally accepted belief that diamond could never be found in the Japanese archipelago which are new in geological terms. An opinion has been long heard, however, diamond might be found in various places in Japan only if looked for more carefully.

Ehime prefessor reluctant to make comment

Diamond may be found throughout Japan (the photo shows an image)
Diamond may be found throughout Japan (the photo shows an image)

   The discoverer of diamond was Tomoyukuki Mizukami, who studies geology at the Nagoya University. He found it after analysing a volcanic rock he collected in a mountainous area in the prefecture some years ago by using laser beam. The size of diamond he discovered, however, was as small as about one thousandth of one millimeter (micro diamond). It was not even visible through an ordinary microscope, and it was not worth an effort to extract on a commercial basis. But the discovery bears geological importance, and whereabouts of the discovery has not been disclosed because of that importance.

   Diamond was made when the carbon changes its atomic configuration under extremely high pressure and temperature in the mantle of the earth 120 kilometers to 150 kilometers below the surface. Diamond in reality is found only in very limited places in South Africa and China's Shandong Province in the world. It has been said diamond can never be found in geologically new places such as Japan.

   Inquired by J-CAST News, Ehime prefectural officials said they did not even know of the diamond discovery in their prefecture. They could not even tell if there was any person who would know if such discovery has been made. The Sumitomo Besshi copper mine in the prefecture was once active in the past and it was said that the production at the mine was the largest in the world. Other than the past story about the copper mine, however, the prefecture has no natural resources to speak of. The news of diamond discovery in the prefecture, therefore, must have only bewildered the officials.

There are cases of micro diamond discovery in metamorphic rocks

   Some people are apparently unable to shake off their dream of finding diamond in Japan in Japan, however. To a question: "Can natural diamond be produced in Japan?" which was posted on the home page of the Geological Society of Japan, Prof. Masaki Enami at the Graduate School of Environmental Studies of the Nagoya University replied:

"Diamond that is big enough to be a gem is extracted from a special type of rocks called the Kimberley rocks. However, micro diamonds are found also in metamorphic rocks that are formed under extremely high pressure. They have been found also in the sedimentary rocks that solidified after metamorphic rocks were once decomposed by weathering. Metamorphic rocks are scattered around wide areas in Japan, and diamond might be found if those rocks were searched thoroughly."

   The micro diamond reportedly discovered in Ehime Prefecture might be an example of such diamond noted by Prof. Enami. Then, there is the possibility that diamond can be found in many places throughout Japan.

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