AUSTRALIAN BOULDER OPAL NECKLACEBOULDER OPAL It has been well documented that this spectacularly colourful form of opal is found primarily in Queensland, Australia (other locations include New South Wales, Canada and Brazil). It is reputed to be harder and more stable than most precious opal. The opal is usually found in fractures and spaces in otherwise impermeable sandstone or ironstone. Boulder opal typically displays bright and vibrant colours. The natural iron stone base of