If you think Australian opal is only white and black you will be surprised to learn that the Australian Boulder Opal is famous for its striking natural artwork with the spectacular opal colours in soft warm iron and manganese oxide matrix patterns. Most known is probably the Yowah nut with the circular patterns of ironstone and center filled opal with amazing colours. But evenly interesting is the Koroit opal which has finer opal veins in a play of different brown tones in the matrix caused by varying concentrations of iron oxide verses manganese oxide.

Read more about the facts of Australian Boulder Opal .