Australia contains and produces over 95% of the world's ENTIRE supply of opal gems. Boulder opal was first discovered in Quilpe, Western Australia, around the year 1870. Almost all boulder opal available today is from Western Queensland's opal-rich fields, confined to an area of about 200 to 300 square kilometers. Boulder opal is found embedded in large boulders of ironstone, which is how it earned its name!2 lbs