How Are Opals Formed?
Opals are often referred to as nature's most mesmerizing gemstone, thanks to their enchanting play of colors that shimmer in the light. But have you ever wondered how these stunning gems come into existence? It’s a fascinating journey deep beneath the earth’s surface, a journey that blends water, time, and the secrets of silica.
Unlike many gemstones that form through heat and pressure, opals arise in a much more delicate process involving water. When rainwater seeps into the ground, it collects silica from sandstone. This silica-rich water fills cracks, voids, and fossils deep within the earth. As the water gradually evaporates over millions of years, it leaves behind deposits of silica, which eventually harden to form Opals. The intricate patterns and vibrant colors we see in opals come from the way tiny spheres of silica are arranged, refracting light into every color of the rainbow.
The Role of the Great Artesian Basin
Australia is known as the opal capital of the world, with more than 90% of precious opals found in its vast landscapes. One of the most famous sources of opals is the Great Artesian Basin, which stretches across several Australian states. Millions of years ago, this region was covered by an inland sea. As the sea retreated, it left behind layers of silica-rich sediment. Over time, rainwater filtered through these layers, creating the perfect environment for opals to form. The result? Stunning varieties like the black opals of Lightning Ridge, the white opals from Coober Pedy, and the boulder opals of Queensland.
Why Are Opals So Unique?
What sets opals apart from other gemstones is their play of color, a phenomenon that occurs due to the unique structure of silica spheres within the stone. When light passes through the silica spheres, it is diffracted, creating flashes of color that shift depending on the angle of light. This dazzling display, known as opalescence, is what makes opals so captivating. In addition to their beauty, opals are also highly prized for their rarity. Finding a high-quality opal with an intense play of color is no easy feat, which is why opals are considered one of the most precious gemstones in the world.
Types of Opals
Opals come in a variety of types, each with its own distinct characteristics. The most valuable is the black opal, known for its dark body color and vibrant flashes of color. White opals, in contrast, have a light, milky body tone, while boulder opals form in ironstone, with a thin layer of opal on the surface. Each type of opal tells the story of the unique geological conditions in which it was formed.
Are you looking for a breathtaking opal to add to your collection? Browse our selection of stunning opal pendants and opal rings at Robinson's Jewelers.