Description
Opal is the second largest gem material produced in Idaho. The Spencer Opal Mine, the largest privately owned gem stone producer in the State, is the major producer of Opal. It occurs as one or more thin layers within common opal partially filling gas cavities within a rhyolite-obsidian flow. The Spencer Mine is the source of pink common opal and pink precious opal. Opal is brittle, heat sensitive, and breaks and scratches easily.
