Beryl properties

Several gemstone species occur in various colors, depending on the presence of impurities or irradiation-induced color centers. Examples are the beryl, comndum, and quart2 families. Quart2 has poor optical properties (RI = 1.55, DISP = 0.013), but becomes of gemological interest when it exhibits attractive colors. Any material can have its color modified by the addition of various impurities synthetic mby, sapphires, and spinel are produced commercially in over 100 colors (2). Synthetic cubic 2irconia has been made in essentially all colors of the spectmm (11), but only the colorless diamond imitation is produced commercially in any quantity. 

Beryl. 385 Beryllium atomic size, 379 boiling point, 374 bonding capacity, 285 chemistry of, 382 electron configuration. 378 heat of vaporization, 374 ionization energies, 379 occurrence, 384 preparation, 385 properties, 381 structure, 381... 

Beryllium, at the head of Group 2, resembles its diagonal neighbor aluminum in its chemical properties. It is the least metallic element of the group, and many of its compounds have properties commonly attributed to covalent bonding. Beryllium is amphoteric and reacts with both acids and alkalis. Like aluminum, beryllium reacts with water in the presence of sodium hydroxide the products are the beryl-late ion, Be(OH)42, and hydrogen ... 

Emerald, Cr " doped beryl, has a beryl structure with the Cr " impurity ions in highly distorted octahedron sites. The discovery of lasing action in emerald stimulated investigation of its luminescence properties. It was established that its tuning range is approximately 730-810 nm, while luminescence consists of a narrow line at 684 nm and a band peaking at 715 nm with similar decay times of 62 ps. The relative intensities of those line and band are different in a- and 7T-polarized spectra (Fabeni et al. 1991). 

Although a particular mineral property may be due to iron impurities, it is generally easier to show this dependance by preparing synthetic samples of variable iron concentration and extrapolating back to the impurity levels of interest in a particular mineral. For example, the iron impurities in blue beryl are at so low a concentration that only weak Mossbauer signals can be obtained. 

The latter wrote in 1798 Klaproth had no sooner discovered the different substances with which he has enriched the science, but they were found in various other bodies and if I may refer to my own processes, it will be seen that after I had determined the characters of chrome, first found in the native red lead, I easily recognized it in the emerald and the ruby. The same has happened with regard to the earth of the beryl. I have likewise detected it in the emerald in which, nevertheless, it was overlooked by Klaproth and myself in our first analysis so difficult it is to be aware of the presence of a new substance, particularly when it possesses some properties resembling those already known. .. (23). 

Beryl had also been analyzed by T. Bergman, F. K. Achard, J. J. Bindheim, and N.-L. Vauquelin, and was supposed to be a calcium aluminum silicate (23). The identity of beryl and the emerald was not suspected until the famous French mineralogist the Abb6 R.-J. Hauy made a careful study of their crystal forms and physical properties and was so struck by the similarity of the two minerals that he asked Vauquelin to analyze them chemically. 

Many chemical properties of beryllium resemble aluminum, and to a lesser extent, magnesium. Notable exceptions include solubility of alkali metal fluoride-beryllium fluoride complexes and the thermal stability of solutions of alkali metal beryllates. 

Cyclosilicates are those compounds with three or more tetrahedra linked in closed, ring-like structures. The ratio between Si and O is 1 3. This group includes the important gem species beryl and the tourmaline group. The 11 members of the tourmaline group display an unusual property known as piezoelectricity. When pressure is applied to a crystal, an electrical charge builds up at either end of it. This makes these minerals useful in pressure gauges and other electrical equipment. Quartz and a few other, less common minerals, also display this property. 

The chemistry of phospholes and related phospholide anion complexes remains a very active area, which also continues to attract the attentions of the theoretical community. Among recent theoretical contributions are a consideration of the stability, structure and bonding in lithium- and beryl-lium-pentaphospholide systems, the aromaticity of the pentaphospholide anion (and its arsenic analogue) as probed by ring currents,the remarkable influence of fluorine-substitution (either at phosphorus or at a ring carbon) on the electronic and thermochemical properties of phospholes,and the effects of methyl and vinyl substitution at various positions on the geometries, relative stabilities and Diels-Alder reactivities of phospholes. An ab initio approach has been used to reinterprete some spectral and thermochemical properties of IH-phospholes. The synthesis and reactivity of phospholes of reduced... 

R. J. Haiiy, a French mineralogist, observes that emeralds and beryl have the same optical properties and therefore the same chemical composition. 

Emerald (Cr3+ Be3Al2(Si03)6, chromium-doped beryllium aluminium silicate or beryl) is a well known gem, and its beautiful green color has been attracted people for a long time. Nowadays, emerald crystal is also known as a tunable solid-state laser material, and its optical properties have been smdied (1-10). 

Properties Fine, hexagonal, hard, refractory crystals attacked vigorously by strong, hot alkali solutions forming methane gas and alkali beryllate. D 1.91 decomposes above 2100C. 

BCjAIjSigOia Beryl from Hoggar, Algeria Properties detailed analysis available [2232]. 

Alkoxyl group exists in the non-polar position of some xanthates and dithiophosphates, which have properties similar to those of alkyl group and produce more froth. For example, etheralkyl carboxylate (ECA), R ,-(OC2H4) 2-OCH2COOH, has been reported as a collector where ni is Cg ig chain and W2 is the number of alkoxyl groups (0-16). Since its Ca or Mg salts with ni = 10, 12, 14, 17 and h2 = 10, 20 30 are soluble in water, ECA is suitable under hard water and low pH (<6) conditions for the flotation of calcium or magnesium minerals, chalcopyrite and beryl with better selectivity. FloatabiUty of Ca minerals is found to linearly decrease with n values and increase with h2 values. 

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