Australian Opal Specimen #23

Gorgeous Opal Specimen from Australia. Opal # 23 measures 3.5" x 2" x 2" and weighs 10.8oz Australian opal forms over millions of years through a process involving silica-rich water seeping down into crevices in the ground. Here’s how it happens: Weathering: Rocks, especially sandstone and other silica-bearing minerals, undergo weathering, releasing silica into the groundwater. Dissolution: Silica dissolves into the groundwater and moves through the soil, especially in arid environments like those in parts of Australia. Sedimentation: When the silica-rich water settles in cavities, cracks, or faults in the earth, it fills these spaces with a gel-like silica solution. Evaporation and Deposition: Over millions of years, the water gradually evaporates, leaving behind layers of tiny silica spheres. As they accumulate, they form a structure that diffracts light, giving opal its famous “play of color.” Formation of Precious Opal: When the silica spheres are uniformly sized and arranged in a grid, they produce precious opal with a rainbow-like effect. If the spheres are irregular, the opal will lack this color play, resulting in common opal, or "potch." Australia’s unique climate and geology have made it one of the prime sources of high-quality opal worldwide, particularly in regions like Lightning Ridge and Coober Pedy.