Azurite is a soft blue copper mineral produced by weathering of copper ore deposits. It is also known as Chessylite after a type of locality in Chessy-les-Mines near Lyon, France. Minerals, carbonates with the chemical formula Cu 3 (CO 3 ) 2 (OH) 2 , have been known since ancient times, and is mentioned in the Natural History of Pliny the Elder with the Greek name kiosk (??????: "dark blue," the English root cyan ) and the Latin name caeruleum . The azurite blue color is very deep and clear, and for that reason minerals tend to associate since ancient times with the blue color of the desert and the winter sky with low humidity. The modern English name of the mineral reflects this association, since both azurite and blue are from the Arabic of the Persian lazhward (????? ), an area known as dark blue stone deposits, lapis lazuli ("blue stone").
Video Azurite
Mineralogi
Azurite is one of two basic carbonate (II) minerals, the other is a bright green malachite. Simple carbonate copper (CuCO 3 ) is not known to exist in nature. Azurite has the formula Cu 3 (CO 3 ) 2 (OH) 2 , with copper (II) with two different anions, carbonates and hydroxides. Small azurite crystals can be produced by stirring a few drops of copper sulphate solution into a saturated sodium carbonate solution and allowing the solution to stand overnight.
Azurite crystals are monoclinic. Large crystals are dark blue, often prismatic. Azurite specimens can be very large to nodular. They are often stalactitic. Specimens tend to light up over time due to weathering of the specimen's surface to malachite. Azurite is soft, with Mohs hardness only 3.5-4. The azurite density is 3.77 to 3.89. Azurite is destroyed by heat, loss of carbon dioxide and water to form a black copper oxide powder (II). Characteristics of carbonates, specimens permeate after treatment with hydrochloric acid.
Color
Optical properties (color, intensity) of minerals such as azurite and malachite are characteristic of copper (II). Many copper (II) coordination complexes exhibit similar colors. As described in the context of the ligand field theory, the resulting color of the low energy d-d transitions associated with the metal center d 9 .
Weathering
Azurite is unstable in the open air compared to malachite, and is often replaced pseudomorphically by bronze. This weathering process involves replacing several units of carbon dioxide (CO 2 ) with water (H 2 O), converting carbonate: azurite hydroxide ratio from 1: 1 to a ratio of 1: 2 malachite: 3 (OH 3 2 (OH) 2 H 2 2 (CO 3 ) (OH) 2 CO 2
From the above equation, the conversion of azurite to malachite is caused by the low partial pressure of carbon dioxide in the air. Azurite is also not suitable with water media, such as saltwater aquarium.
Maps Azurite
Usage
Pigments
Azurite is not a useful pigment because it is unstable in the air. However it is used as a blue pigment in ancient times. Azurite is naturally occurring in the Sinai and the Eastern Desert of Egypt. Reported by F. C. J. Spurrell (1895) in the following example; a shell used as a palette in the context of the Fourth Dynasty (2613 to 2494 BC) in Meidum, a cloth over the face of the Fifth Dynasty (2494 to 2345 BC) mummies also in Meidum and a number of Eighte Dynasties (1543-1292 BC). ) Wall painting. Depending on the level of fineness that has been pounded, and the basic content of carbonate carbonates, it provides a variety of blues. It has been known as blue mountain or Armenian stone , otherwise it was formerly known as Azurro Della Magna (from Italian). When mixed with oil, the color turns green. When mixed with egg yolks, the color becomes gray-green. It is also known as blue bice and blue verditer, although verditer usually refers to pigments made by chemical processes. Older examples of azurite pigments may show a more greenish color due to weathering into bronze. Many azurites are labeled lapis lazuli , a term used for many blue pigments. As the chemical analysis of painting from the Middle Ages increased, azurite was recognized as the main source of blues used by medieval painters. Lapis lazuli were mainly supplied from Afghanistan during the Middle Ages, whereas azurite was a common mineral in Europe at the time. A sizable deposit was found near Lyons, France. It was mined since the 12th century in Saxony, in a silver mine located there.
Heating can be used to distinguish azurites from pure natural ultramarine blue, more expensive but more stable blue pigments, as described by Cennino D'Andrea Cennini. Ultramarine is heat resistant, while azurite turns into black copper oxide. However, gentle azurite heating produces the dark blue pigments used in Japanese painting techniques.
Jewelry
Azurite is used occasionally as beads and as a jewelry, and also as an ornamental stone. However, the tenderness and tendency to lose the dark blue color therefore limits such use. Heating destroys azurite easily, so all installation of azurite specimen should be done at room temperature.
Collecting
The intense color of azurite makes it a popular collector stone. However, bright light, heat, and open air all tend to reduce the color intensity over time. To help preserve the dark blue color of pure azurite specimens, collectors should use cold, dark, and closed storage environments that are similar to their original natural environment.
Prospecting
Although not the main ore of copper itself, the presence of azurite is a good surface indicator of the presence of rotted sulphide copper ore. It is commonly found in association with a very chemically similar malachite, producing a striking color combination of dark blue and bright green that strongly indicates the presence of copper ore.
History
The use of azurite and malachite as an indicator of copper ore indirectly leads to the name of nickel elements in English. Nickeline, the main nickel ore known also as niccolite, grows on the surface into a green mineral (annabergite) that resembles malachite. This resemblance generates an occasional attempt to kiss nickel in the belief that it is copper ore, but the effort always ends in failure because high melting temperatures are necessary to reduce nickel. In Germany this deceitful mineral came to be known as kupfernickel , literally "copper demon". Swedish alchemist Baron Axel Fredrik Cronstedt (who had been trained by Georg Brandt, the inventor of a nickel-like metal cobalt) realized that there might be a new metal hiding inside the kupfernickel ore, and in 1751 he managed to melt kupfernickel to produce previously unknown ( except in certain meteorite metals) are silvery-white, like iron. Logically, Cronstedt named his new metal after the nickel section of kupfernickel .
Gallery of azurite mineral specimens
See also
- Basic copper carbonate
- List of inorganic pigments
- Mineral list
References
Further reading
- Gettens, R.J. and Fitzhugh, E.W., "Azurite and Blue Verditer", in Artist Pigments: A History Handbook and Their Characteristics, Vol. 2: A. Roy (Ed.) Oxford University Press 1993, p.Ã, 23-35
External links
- Ã, Spencer, Leonard James (1911). "Azurite". EncyclopÃÆ'Â|dia Britannica . 3 (issue 11). p.Ã, 86. Source of the article : Wikipedia
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