Opal is a gemstone with a color-changing effect. Pliny, a famous natural scientist in ancient Rome, once described it as follows: “オパールの石の上に, you can see the flame of ruby, アメジストのような色の斑点, and the emerald sea. 緑, the five colors are colorful, blending together, and beautiful.” 古代中国では, opal was regarded as a palace treasure. In the Ming and Qing Dynasties, there were many titles such as white gemstone, lizhu, flashing mountain cloud, and colorful stone. Because Opal integrates the characteristics of a variety of precious gemstones, with its gorgeous colors and luxurious quality, it is deeply loved by people.
Opal is mainly composed of water-containing silica, with glassy luster to waxy transparent, 透明から半透明, と硬さ 5.0-6.5. Its color is mostly egg white. Because the composition contains trace impurity elements such as iron, 銅, マンガン, ニッケル, 等, it also has gray-black, 青, 茶色と他の色. 特に, its luster has a color-changing effect, changing to deep purple or deep brown purple. Its surface is as gorgeous as a peacock feather, which changes with the change of light, showing a variety of colors such as red, オレンジ, 青, そして緑, すごいですね.
As a mineral, opal is divided into precious protein or gem-grade opal, and ordinary opal. 一般的に, precious opal is called opal. Only opal can produce an effect. This feature has been a mystery for a long time, until opal was placed Under an electron microscope of more than 10,000 回, it will be found that its internal structure is composed of countless tiny silicon dioxide spheres regularly arranged in three-dimensional space. The gap between the spheres acts as a grating for light, namely Diffraction phenomenon. The wavelength of the colored light (いわゆる “火”) produced by diffraction is mainly determined by the angle between the incident light and the sphere and the diameter of the sphere. したがって, when the gem is rotated, the angle of the incident light will change, thereby changing the diffracted light. The wavelength changes the color and produces a brilliant iridescence. 一方で, ordinary opal has different diameters and disorderly arrangement of the internal tiny spheres. Under the irradiation of light, it will scatter irregularly and appear opalescent color. It cannot produce special optical effects, so it cannot change color. Its value is much lower. Precious opal.
Opal is mainly produced in the ancient weathering crust formed by exogenous leaching and in the hydrothermal fluid after volcanic period. The most famous high-quality opal is produced in Australia. It has a history of more than 100 years since its discovery. It accounts for more than 90% 世界の総生産量のうち. 加えて, メキシコ, 米国, ブラジル, Honduras, チェコ共和国, スロバキア, and Indonesia also produced output. Many large and beautiful opal treasures have been found in the world. 例えば, the largest piece, named “Puma Opal”, weighs 61.3 kg; the one is of good texture and has a lightning-like yellow, green and blue color. The famous opal with a crimson pattern that flickers and complements each other, 重さを量る 711 カラット; the two black opals named “Lady Flame” 重さを量る 233 carats and the name “Light of the World” 重さを量る 273 grams are all produced Australia.