Opal information

What is opal? Opal is a true precious stone which occurs in many varied forms. Opal is amorphous silica with a water content varying from one to twenty percent, depending on the porosity and degree of hydration. Precious opal usually contains from six to ten percent water. The chemical formula for opal is SiO2·nH2O What causes the play of color and different patterns in opal? In the mid 1960's a group of scientists at the Commonwealth Scientific and Industrial Research Organization (Australia) solved this mystery and put an end to all previous theories. By using a newly developed electron microscope...