Lapis-lazuli

Lapachic acid Lapacol [84-79-7 Laparoscope Lapelloy Lapis Lazuli Lapis lazuli [1302-85-8] Laplace pressure Laplace s equation... 

Ultramarine Pigments. Ultramarines are derived from lazurite [1302-85-8] (lapis lazuli), a semiprecious stone, which was the natural source of ultramarine blue for hundreds of years. Ultramarines can be prepared in many shades. Examples of commercially significant ones ate ultramarine blue, ultramarine violet, and ultramarine pink. The ultramarine pigment having a green shade can also be prepared but it is not commercially available. The first German patent issued in 1877 was for the manufacture of ultramarine red (42). 

Azulminsaure,/. azulmic acid, azur, azurblau, azum, a. azure, sky-blue. Azurstein, m. lapis lazuli, azyklisch, a. acyclic. 

Lasur, /. azure azurite glazing, glaze. — m. lapis lazuli. 

Lasurit, m. azurite lapis lazuli, lasur-lack, m. transparent varnish, -schleif-lackf m. transparent flatting varnish, -spat, m. lazuUte. 

Lasorstein, m. lapis lazuli. — unechter —, false lapis lazuli, chessylite. lateinisch, a. Latin roman (letters). 

FIGURE 15.15 The blue stones in this ancient Egyptian ornament are lapis lazuli. This semiprecious stone is an aluminosilicate colored by S2 and S, impurities. The blue color is due to S3 and the h i nt of green to S2. ... 

The sulfur analog of hydrogen peroxide also exists and is an example of a polysulfane, a catenated molecular compound of composition HS—S —SH, where n can take on values from 0 through 6. The polysulfide ions obtained from the polysulfanes include two ions found in lapis lazuli (Fig. 15.15). 

C03-0102. Calculate the mass percentages of all of the elements in the following semiprecious minerals (a) lapis lazuli, N34 AI3 Si3 O12CI (b) garnet, Mgg AI2 (Si04)3 (c) turquoise,... 

Zeolites are structurally related to colorless sodalite, Na4Cl[Al3Si3012], and to deeply colored ultramarines. These have aluminosilicate frameworks that enclose cations but no water molecules (Fig. 16.25). Their special feature is the additional presence of anions in the hollows, e.g. Cl-, S()4, S2, or S. The two last-mentioned species are colored radical ions (green and blue, respectively) that are responsible for the brilliant colors. The best-known representative is the blue mineral lapis lazuli, Na4S (.[Al3Si3012], which is also produced industrially and serves as color pigment. 

Formerly derived from the natural mineral lapis lazuli, ultramarine blue pigments have, for more than a century, been manufactured synthetically. The materials used in the manufacture of ultramarines are china clay (a hydrated aluminosilicate), sodium carbonate, silica, sulfur and a carbonaceous reducing material such as coal tar pitch. For the manufacture of the blue pigments, the blend of ingredients is heated to a temperature of 750 800 °C over a period of 50-100 h, and the reaction... 

Shen This talisman depicts a reed tied in a circle to represent the orbit of the sun and, therefore, it became a symbol of the cycle of time and eternity. It was commonly made of lapis lazuli or carnelian and laid on the dead to ensure eternal life. Symbolically, the Shen is related to the symbol of a snake forming a circle by biting its tail, called an ouroboros, which became an important alchemical symbol. 

Obviously, in solution, 83 is not stable against oxidation. It is stable in the mineral lapis lazuli, and the industrial ultramarine blue pigment [28]. In these materials, the radical 83 is encapsulated in the -cages of the sodalite structure, which protects it against oxidation. In ultramarine pigments, another radical anion polysulfide, 82 , has been observed. 

A remarkable example of a persistent radical anion is the semiprecious stone, lapis lazuli, known and appreciated as a pigment since ancient times. The species imparting the blue hue is trisulfur radical anion, S , accompanied by variable fractions of S, which introduces a green tint the sulfur radical anions are incarcerated... 

Research in zeolites has also branched out to try to prepare new materials by incorporating various molecules and ions in the cages of these microporous and mesoporous structures. An early example of this was the preparation of the pigment ultramarine used in many paints and colourants. It is based on the zeolite sodalite (SOD) structure and contains 83 ions trapped in the cages this is the same anion found in the mineral lapis lazuli, to which it imparts the beautiful deep blue colour. Treatment of zeolites such as Na-zeolite Y with sodium vapour traps Na4 ions in the cavities, which impart a deep red colour. 

Sulfur forms a series of homoatomic dianions catena-S (x = 2-8), which, without exception, have unbranched chain structures in the solid state.The electrochemical reduction of cyclo-Sg in aprotic solvents occurs via an initial two-electron process to produce catenaS P In solution, catena- and other long-chain polysulfides, e.g. catena- and catenaSi, dissociate via an entropy-driven process to give radical anions S (x = 2-4), including the ubiquitous trisulfur radical anion (x = 3). This intensely blue species is the chromophore in the mineral lapis lazuli, which is used in the manufacture of jewellery. 

Q The ion S,- contributes to the colour of the mineral lapis lazuli and synthetic materials of a similar structure called ultramarines. 

The deep blue colour of lapis lazuli is due to the S/ radical-ion, but in the ultramarines the colour ranges from deep blue to green the green materials containing a greater proportion of S.," ions. 

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