The Queensland opal fields are within a belt of deeply weathered Cretaceous sedimentary rocks, a distance of about 1000 km. The opal occurs as a filling or lining between the concentric layers or in radial or random cracks. And this matrix opal is where the opal occurs as a network of veins or infilling of voids or between grains of the host rock. Please view its video here to see its shine of brilliant colors - red, orange, green and yellow.