The man, a former employee of the museum, is alleged to have been secretly working the 30 mines in Kongsberg, West of Oslo, from the year before they officially closed in 1992.
The man has been charged with grand larceny, unlicensed use of explosives, and breaching Norway's Cultural Heritage Act.
The case, which is expected to last three days, started at Kongsberg District Court on Monday.
The man was arrested in May 2012 as he left a mine with silver ore he had mined.
At his home, police seized silver with an estimated value of nearly two million kroner ($334,000).
"Of course it was a great satisfaction in that the first man we were able to expose was one of the big fish," Alfhild Skaardal, director of the Norwegian Mining Museum told TV 2.
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Skaardal began investigating charges of theft when she came in as the museum's chief in 2009.
The man's lawyer, Frederick Neumann, would not comment on the case or the charges.