Unidentified lamp

This lamp was my Great-Uncle´s who lived most of his adult life in Rochester, Minnesota. He never married and had quite a collection of small valuables. It is REALLY heavy so guessing it is made out of some kind of medal and at first thought the Japanese motifs were inlaid but wondering if it isn't painted on. Still works but as you can see the cord is a little (or a lot frayed). I know he traveled a bit but can´t seem to find any information on it and the only mark is an M in a square on the neck hardware. Also wondering if it is ok to rewire it without hurting any value for the future. Any information or direction for further research would be very welcome.