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Icelandic Spar. How is he interesting?
To begin with, we will clarify what is Icelandic spar. This is a transparent variety of calcite, often colorless, but sometimes can have a slight shade caused by various impurities. This mineral has been known for a long time and the first mention of it dates back to 1300-1400 years.
Even in antiquity, people realized that Icelandic spar has unusual properties. So the Vikings in the Middle Ages used it as a compass and determined the position of the sun in the sky, looking through a piece of it at the sky. Later, scientists explained the physical meaning of this application. This is due to the fact that Icelandic spar is characterized by a high birefringence of light, that is, it is a polarizing filter. Therefore, if you look at the sky through a piece of spar in cloudy weather, you can understand where the light is maximally and minimally polarized, and therefore determine the position of the sun. Since sunlight is not polarized, but only partially polarized by clouds in cloudy weather, the area of the sky that will be lighter through the stone will indicate the position of the sun.
In the modern world, Icelandic spar is actively used in optics, again due to the birefringence property. It is indispensable in polarizing microscopes and other devices for which radiation strength is needed.
В геммологической практике бывают весьма увлекательные случаи с диагностикой ювелирных вставок
Но помимо редкости цвета и высокой стоимости таких камней, многие розовые камни выделяются одной замечательной особенностью – они проявляют плеохроизм, то есть в зависимости от положения осмотра камня он может иметь дополнительные оттенки – оранжевый или пурпурный.
Currently, gemstones are produced by two fundamentally different technological methods - the High Pressure - High Temperature method (“HPHT”, High-pressure & High-temperature) and the Chemical Vapor Deposition (“CVD”, Chemical vapor deposition) method. The "HPHT" method is the most tested classical synthesis method, which can be used both carbon deposition on diamond from flux melts and catalytic reactions. In "CVD" synthesis, diamond growth occurs on a seed during carbon deposition mainly from a gaseous medium at relatively low temperatures and pressures.
Jewelry and precious stones are just such a category of goods, when buying which you need to pay attention to many criteria.
Sogdianite is a rather rare mineral and more often it can be found as a collection material (moreover, in systematic collections), and it is extremely rare in jewelry.