I wonder if this mine did originate in China, but was of Japanese design and manufacture? I have been told by a knowledgable source in China that the Japanese made many types of ordnance there during the occupation that never appeared in any official Japanese documentation. (One example would be the "Manchukuo" grenade, of which a few examples came up for sale a few years ago.)
To me, this mine looks Japanese. The quality of manufacture is better than the Chinese pieces I've seen from the period. It has machined features, which seems unlikely for a Chinese mine, although the Japanese could have modified existing mine castings. Also, the physical appearance of these mines is fairly consistent, while Chinese ordnance from the period tended to vary a great deal, as if the design was only an approximation. The casting is rougher than on Japanese grenades, but this could be because they were using the resources available to them in China. The black finish on it looks the same to me as the black (lacquer?) finish that I've seen on Japanese grenades. The Chinese had been involved in a civil war well before the Japanese invaded, so I don't see why they'd bother putting a nice finish on a mine.
My guess is that these are Japanese-made mines, made in China. I look forward to finding out the answer.
Rob
