Boulder opals are mined in Queensland Australia. Most popular mining towns are Quilpie and Winton but opal mines are spread over huge are of thousands of kilometres and many opal mines are 2-300 kilometres from any town and the summers are extremely hot in the outback deserts of Australia. Boulder opal is formed in veins thru ironstone material and have an exciting arrange of colours and mixtures. Opal can be clean faced opal or have inclusions of natural brown potch, either way most opals are unique. Source your Boulder opals direct from opal miners and opal wholesalers and dealers for your single gem opal or parcel black opals from Quilpie or Winton Australia