Common Opal
Pictures of Common Opal

Common opal is a hydrous silicon dioxide material that does not exhibit a "play of color". Common opal can be cut into stones, it can be attractive and it can accept a high polish. It simply lacks the play of color displayed by precious opal. Common opal is sometimes called "potch". Common opal usually has very little commercial value compared to precious opal; however, some exceptional pieces are sold for nice prices. The specimen at right is a stone cut from Morado Opal from Mexico. The specimen below is a cabochon of blue Owyhee Opal from Oregon. Both of these are "common opal", yet they are highly attractive stones.