How opals are formed.

Opals are formed underground around the great artesian basin. Once being an organic matter silted over and stuck in suspended dirt. The organic things like shells, bones and wood deteriorate and leave a cavity of the shape of its former self. Silica over millions of years seep into the cavities filling up the cavity to form opal. When the spheres are stacked neatly they produce precious play of color.

Видео How opals are formed. канала Black Opal Direct