Boulder opals pendants are generally larger than most opals and have good natural patterns that make each pendant so unique. 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 opals are formed in veins of ironstone and most have an exciting array of colours and mixtures. Opal can be clean faced opal or have inclusions of natural brown potch, either way most opals are unique.