A federal investigation has determined that an arsonist is responsible for a fire at the Lucky Friday Mine on July 26 in Idaho's panhandle.
About 170 miners were evacuated when the fire was detected. No one was injured. A second smaller fire at the silver mine on July 5 is still under investigation.
The Mulan mine was the scene of a collapse in April, which claimed the life of a Hecla Mining employee. Hecla is the largest silver producer in the United States.