Opal has been found at many locations in Idaho, and mines there have produced it since the early 1900s. Most of the production has been from small mining operations and open cuts worked by two or three people. There have also been a few fee mining locations where individuals can pay a fee, search for opal, and keep any that they find.

Today, commercial opal production in Idaho occurs at a few locations near the town of Spencer. The largest producer is Spencer Opal Mines. They mine precious opal and sell rough and cut stones. They also have an area where visitors can search through material trucked in from their mine and keep any opals that they find.