Opal is an amorphous mineraloid that comes in many unique varieties based on the location it was sourced from. The two main types are Precious and common Opal. When speaking of opal people are generally referring to precious opal. The majority of precious opal is mined in Australia where over 96% of the world’s supply is produced. Notable mines in Australia include Coober Pedy, Lightning Ridge, Lambina, Mintabie, Andamooka, Yowah, Koroit, Jundah, Winton and Quilpie. Other countries that produce both precious and common opal include; Brazil, Czech Republic, Ethiopia, Guatemala, Honduras, Hungary, Indonesia, Mexico, Nicaragua, Peru, Slovakia and the U.S.A.