Beryllium silicate

Beryllium compounds (except aluminium beryllium silicates) Bis(chloromethyl)ether (BCME)... 

Beryllium compounds with the exception of aluminium beryllium silicates Cadmium oxide Cadmium sulphate... 

The glasses used by Steenbock in his original compositions were mixtures of calcium aluminosilicates and beryllium silicates but, as Dreschfeld reported in 1907, subsequent developments moved away from the use of beryllium compounds. Published chemical analyses in the period to 1916 (Voelker, 1916a Greve, 1913 Watts, 1915) confirmed Dreschfeld s statement. In the following we shall refer to these as oxide glasses. 

Beryllium phosphate see Beryllium and beryllium compounds) Beryllium silicate see Beryllium and beryllium compounds)... 

The study of coordination compounds of the lanthanides dates in any practical sense from around 1950, the period when ion-exchange methods were successfully applied to the problem of the separation of the individual lanthanides,131-133 a problem which had existed since 1794 when J. Gadolin prepared mixed rare earths from gadolinite, a lanthanide iron beryllium silicate. Until 1950, separation of the pure lanthanides had depended on tedious and inefficient multiple crystallizations or precipitations, which effectively prevented research on the chemical properties of the individual elements through lack of availability. However, well before 1950, many principal features of lanthanide chemistry were clearly recognized, such as the predominant trivalent state with some examples of divalency and tetravalency, ready formation of hydrated ions and their oxy salts, formation of complex halides,134 and the line-like nature of lanthanide spectra.135... 

Emerald is a variety of beryl, a beryllium silicate, with a hardness of 7.5 to 8. It has a beautiful deep green color, and it is one of the most expensive gems, sometimes outranking diamond in value. The green color results from small amounts of chromic oxide (Cr203). The oldest emerald mines were in Egypt near the Red Sea, but the best emerald mines today are in Colombia. There are others in Brazil, Pakistan, and Africa synthetic emeralds of excellent quality have also been manufactured. 

Aquamarine, like emerald, is a transparent variety of beryl, or beryllium silicate. Its light blue to blue-green color results from small amounts of iron in the crystal. Like most beryl stones, it measures 7.5 to 8 on the Mohs hardness scale. Most aquamarine gemstones come from Brazil. 

SYNS MANGANESE ZINC BERYLLIUM SILICATE ZINC MANGANESE BERYLLIUM SILICATE... 

SYNS BERYLLIUM ORTHOSILICATE BERYLLIUM SILICATE BERYLLIUM SILICIC ACID... 

TRIS(OCTAMETHYLDIPHOSPHORAMIDE-Op,Op )-, (OC-6-11)-, DIPERCHLORATE see TNK400 MANGANESE ZINC BERYLLIUM SILICATE see BFS750... 

Approximately fifty beryllium minerals occur in nature and over half of these minerals are silicates. Beryllium is mined primarily from these sifi-cates, including beryl, Al2Be3Si60i8, 5 percent (wt.) berylfium, and bertran-dite, Be4(0H)2Si20y, 15 percent (wt.) beryllium. The world resources of beryllium are estimated at approximately 80,000 tons. Other common beryllium silicates include chrysoberyl, BeAl204, and phenacite, Be2Si04. 

Romannikov et al. studied the catalytic properties of beryllium-silicates with a zeolite-type structure. Methanol conversion yielded primarily olefins, while on the isostructural aluminum-silicate catalyst paraffins and aromatics were obtained. The methanol conversion was considerably higher on the [AlJ-ZSM-5 than on the [Be]-ZSM-5, except in one example (Table 12). 

Be2Si04 BERYLLIUM SILICATE (PHENACITE) 185 C2CI2[g] DICHLOROACETYLENE (GAS) 227... 

Sodium Beryllium Silicate.— Hautefeuille and Perrey (1890 II and 1893 t) in manner analogous to their corresponding potassium compounds by fusing the constituents of a beryllium nephdene in excess of sodium vanadate, obtain crystals of a silicate varying between wide limits and which they concluded were rnixtures of simpler types. 

Ann.nlfs de ehim. et ilc phys.. (6) 20. 447-474. Artilidally prcKlucc phenacite. licryl and a number of iineertaiii soditnu and >f>tasshnn l crylliiini silicates and basic beryllium silicates. 

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