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Precious stones
Published in Francis P. Gudyanga, Minerals in Africa, 2020
Beneficiation from ores is as described in section 6.1.2. In order to fill in surface-reaching cracks and improve their clarity and stability, most emeralds are oiled as part of the post-lapidary process. Cedar oil or other liquids including synthetic oils and polymers of similar refractive index, such as opticon, is used. Fractures on emerald stones are often waxed with glass or resin to stabilise the stone and make the fractures and surface-reaching inclusions less visible. Reduction of visibility of inclusions is often done by heating and drilling.
Atomic and Molecular Origins of Color
Published in Mary Anne White, Physical Properties of Materials, 2018
Interestingly, emeralds, which are green, also derive their color from Cr3+ ions, this time in a material with composition Be3Al2SiO6 (known as beryl when pure). The Cr3+ in this structure is in a very similar environment to that in ruby, but it experiences a different crystal field strength. The difference in color subtly illustrates the importance of the magnitude of the crystal field strength. Determination of whether the crystal field strength is less than or greater than in ruby is left as an exercise for the reader.
Emerging Mirror Technologies
Published in Paul Yoder, Daniel Vukobratovich, Opto-Mechanical Systems Design, 2017
William A. Goodman, Paul R. Yoder
Silicon carbide, also known as carborundum, is a compound with equal portions of silicon and carbon atoms. It was first produced by Edward Acheson around 1893. Acheson developed an electric batch furnace to produce the material in bulk, and the Carborundum Corporation was born. Interestingly, natural crystals of silicon carbide, also known as the mineral moissanite (moys-uh-nite), were not discovered until 1904. Professor Moissan found the first samples of the mineral while exploring in California and Arizona. Some 85 years later, Kurt Nassau created moissanite gem stones. These gem stones are harder than sapphire, ruby, or emerald and register 9.25 on the Mohs hardness scale, a gemstone hardness that is second only to diamond. Moissanite gems have an index of refraction (n = 2.69) greater than diamond (n = 2.42) and 2.4 times the spectral dispersion. Mirrors made of silicon carbide are discussed in considerable detail in Section 6.5.4 of this volume.
Systematic Review of Research Trends in Engineering Team Performance
Published in Engineering Management Journal, 2023
Ramy I. Hindiyeh, William K. Ocloo, Jennifer A. Cross
Three reputable platforms, COMPENDEX, EBSCO, and IEEE Xplore, were selected for the research. After consulting with library experts and pre-testing the platforms that the experts initially suggested, the researchers chose these three platforms. The pre-testing included using potential inclusion search terms on several platforms, including COMPENDEX, EBSCO, IEEE Xplore, ABI, and Emerald. After reviewing the number of results from each platform and comparing these results with the number of results that passed the inclusion criteria, the researchers found that three platforms provided a higher percentage of relevant results that passed the inclusion criteria. The following states the percentage of relevant or applicable search results from each platform based on the preliminary platform testing: COMPENDEX 76%, EBSCO 75%, IEEE Xplore 63%, ABI 30%, and Emerald 14%. Based on this evaluation, the researchers concluded that three platforms resulting in the highest applicable search results included COMPENDEX, EBSCO, and IEEE Xplore, the most relevant research platforms.
Filtration efficiency investigation of mesh fabrics by polytetrafluoroethylene filament with surface static electricity
Published in The Journal of The Textile Institute, 2019
Haiwen Mao, Pibo Ma, Gaoming Jiang
Being called as ‘Emerald jade seal’, natural mineral tourmaline is boron-bearing silicate mineral with trigonal crystal structure. The chemical formula of the tourmaline is Na (Mg, Fe, Mn, Li, Al)3Al6[Si6O18] •[BO3]3(OH, F)4, containing trace elements such as: V, Cr, Zr, Mn, Ti, Sr, and Ga. The tourmaline can be classified as aphrizite, tsilaisite, uvite and buergerite based on its main components. The tourmaline is a type of intelligent and functional ecological material applied in electronics, chemical, health field and environmental protection. The characteristic and important feature of tourmaline is the generation of spontaneous and permanent poles which can produce an electric dipole. It is capable of radiating far infrared energy, permanently releasing negative ions, producing an electric field and releasing rare microelements (Henry Darrell et al., 2011; Ma, Zhong, Mao, Yu, & Miao, 2016; Yavuz, Yavuz, & Sasmaz, 2006).