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Main jade producing countries. Jade is an umbrella term for two different types of decorative rocks used for jewelry or ornaments.Jade is often referred to by either of two different silicate mineral names: nephrite (a silicate of calcium and magnesium in the amphibole group of minerals), or jadeite (a silicate of sodium and aluminum in the pyroxene group of minerals). [1]
Some people assumed the color was due to copper because copper compounds often have blue and green colors. [20] A 1985 study suggests that the blue-green color results from quantities of lead and water in the feldspar. [20] Subsequent 1998 theoretical studies by A. Julg expand on the potential role of aliovalent lead in the color of microcline ...
Variscite has been used in Europe to make personal ornaments, especially beads, since Neolithic times. Its use continued during the Bronze Age and in Roman times, although it was not until the 19th century that it was determined that all the variscite used in Europe came from three sites in Spain, Gavá (Barcelona), Palazuelo de las Cuevas (Zamora), and Encinasola (Huelva).
The meaning of crystal versus glass changes according to the country. The word "crystal" means, in most of the Western world, lead glass, containing lead oxide.In the European Union, the labeling of "crystal" products is regulated by Council Directive 69/493/EEC, which defines four categories, depending on the chemical composition and properties of the material.
Color code: red = O, green = Cu, gray = C, white = H) Azurite has the formula Cu 3 (CO 3) 2 (OH) 2, with the copper(II) cations linked to two different anions, carbonate and hydroxide. It is one of two relatively common basic copper(II) carbonate minerals, the other being bright green malachite. Aurichalcite is a rare basic carbonate of copper ...
The Byzantines perfected a unique form of cloisonné icons. Byzantine enamel spread to surrounding cultures and a particular type, often known as "garnet cloisonné" is widely found in the Migration Period art of the "barbarian" peoples of Europe, who used gemstones, especially red garnets, as well as glass and enamel, with small thick-walled cloisons.
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