Olivine is a magnesium-iron silicate mineral, belonging to the orthorhombic crystal system. The refractive index is 1.654-1.690, and the birefringence difference is quite high as 0.036. From the table of the gemstone, the ridgelines of the bottom facet become overlapping The double shadow is because of the high birefringence difference, the dispersion rate is 0.020, the specific gravity is 3.27 に 3.48, and the hardness is 6.5 に 7. In addition to the typical yellow-green, olivine has other colors such as colorless, yellow or brown. This is due to the relationship between magnesium and iron, and brown is the result of oxidation of yellow-green iron olivine.
The most common olivine in the market is mainly faceted cut, and there are many olivines cut into egg noodles. Because large olivine crystals are quite common, olivine gems with high carat numbers are easy to obtain and the price is very high. Approachable.
Olivine is characterized by its very high birefringence difference. As long as you use a handheld 10x magnifying glass to observe the ridgeline of the bottom facet from the desktop, you can see obvious double shadows, even on large faceted olivines as long as you get close. The double shadow phenomenon can be found by checking. This is the easiest olivine detection method.
一般的に, the clarity of faceted olivine is very high, and it is not easy to find the inclusions with the naked eye. When choosing olivine, the color is the priority, because this is the most important factor in determining the price of olivine. The more intense the color is. For the election.
In ancient Egypt, St. John’s Island on the Red Sea was the main producing area of olivine. The olivine mining here has a history of more than 3,500 年. Later, other producing areas have been discovered one after another. 今日, the main producing areas of olivine in the world are Myanmar, スリランカ, ブラジル, 南アフリカ, the United States and Australia.