留学生作业代写：The appreciation of the Crystal

下面为大家整理一篇优秀的paper代写范文- The appreciation of the Crystal，供大家参考学习，这篇论文讨论了水晶。世界各地几乎都有水晶岩矿的发现，其广泛分布在富含二氧化硅热液的地下矿脉当中，水晶是一种相当常见且公众接受度很高的宝石品种，是珠宝中最为畅销的品种。水晶的主要化学成分是二氧化硅，品种多而繁杂，在鉴赏评定过程中都有着各自的品评标准。

Crystal is the best-selling variety in jewelry, this article through to Crystal Gem characteristic, the quality evaluation standard and The imitation several aspects start, to the crystal and the synthetic crystal Distinction appraisal and the crystal Quality appreciation carries on the analysis research.

Almost all around the world, the discovery of crystalline rock, widely distributed in the underground veins rich in silica hydrothermal, crystal is a very common and highly accepted gem variety. The main chemical composition of the crystal is silica, in the crystal due to the formation of different trace elements of the color heart will produce different color appearance, such as Purple crystal, yellow crystal, brown crystal, pink crystal and so on; According to the difference of the associated vein of crystal deposit, there are many kinds of inner inclusions, such as rutile, Sun Stone, mica, chlorite and so on, in the crystal, and the crystal varieties containing fibrous inclusions are called hair crystals. The crystalline species containing green flakes or cloud-like inclusions are called green Ghosts. Crystal variety and complex, in the appreciation of the process have their own evaluation standards.

Crystal is a quartz crystalline mineral, mainly composed of silica, Mo's hardness of 7, when the perfect crystallization of silica crystals, not perfect crystals for quartz. Color Crystal composition contains chromium, manganese, copper, iron and other color ions, the content of the color of the color of the crystal has a direct impact on the depth: manganese ions and iron ions can make the crystal purple, iron ions make the crystal yellow, manganese or titanium ions can make crystal pink-peach red.

Crystal Crystal has a relatively stable 0.009 birefringence, in a certain direction through the crystal crystal or faceted body to see the ghosting effect. Under the orthogonal polarization, crystals can see a unique one-axis crystal interference diagram: The black 10-shaped cross arm in the center of the hollow style, and present pale green or pale pink, known as bovine eye interference phenomenon. At the same time, because crystals are no cleavage crystals, the rupture of the mineral crystals can produce irregular rupture ports, the fracture is shell-like or sawtooth-shaped.

Crystal crystals produce electrical charges themselves when subjected to pressure, so the charge produced by the crystals after a certain frequency of friction can adsorb finely-grained pieces of paper. Crystals are easily broken by heat, so if the crystals are heated or placed beside the flames, be careful to cool the crystals slowly.

The natural crystal growth environment is more than 80 million years in the underground or caves need to undergo the growth time to crystallize, and crystallization of six square crystal crystals all of the crystal tip will be toward the center of the hole in the direction of the rule growth. The growth phenomenon can be observed in crystal holes or crystal pots sold on the market.

Most color gems will color as the first of the evaluation, and for the crystal color and clarity of the same importance, which is also due to the crystal itself production is relatively large, the number of choices can be more reason.

Color evaluation process of color gems follow the "positive, strong, Yang, uniform" standard, so crystal crystal color bright, rich, uniform, high color purity and does not contain gray, Brown, black and other miscellaneous tones, was identified as crystal high quality varieties. In the color crystal, pink crystal is the best, purple crystal is required to be rich and gaudy but not black, yellow crystal to kumquat color and do not contain green or lemon color tones for the best. In the case of a fibrous inclusion, such as rutile, the crystal is considered to be the most valuable variety for its completely colorless blond hair. Color evaluation mainly depends on the visual sense of the naked eye to determine, the assessment process to be placed in the crystal on the reflection of White Paper on the multi-directional observation, the final conclusion. The industry does not have a unified evaluation of the color of the crystal, each color of the crystal varieties will have their own slightly different levels of classification.

In addition, crystal evaluation of the requirements for clarity is relatively high, usually require crystal interior no obvious inclusions, impurities, etc., natural crystals in the formation process, to the sun observation can see even fine light horizontal lines, which is the natural crystal identification of a typical feature. The interior of the crystal can often be found in a cloud-like or cotton-like package, some of the crystal interior also has a black or other color of the mottled impurities, these are due to the crystal in the growth process of the geological environment affected by the process, in the design and cutting processes need to be the crystal quality of the parts removed. In addition, Crystal crystal interior contains a variety of mineral inclusions, some of the inclusions can form some landscape or just to form a deity, such as auspicious meaning or meaning of the image, known as "gem-grade ornamental Stone", its value is higher. The crystalline view-level ornamental stone containing the inclusions can be divided into the following three types according to the time that the inclusions are formed in crystal crystals:

The first form is "whole package" crystal, the body and crystal are formed at the same time, mostly keep the crystal crystallization of the original, and crystal together experienced hundreds of millions of years of long growth process, very little affected by other natural environment; the second form is "semi-encapsulated" crystals, most of which are caused by the influence of the Earth's external forces after crystal crystallization. A portion of the crystalline material is encased in the crystal, which is influenced by the natural environment and has a lower value. The third form is called "the Skin" crystal, Formed by the erosion of crystals of minerals that coexist with crystals, in the later period, the combination of the position will be due to the crystal with the crystal bond is not strong enough to fall off, so that the surface of the crystal formation of a wide range of potholes or eclipse, which in some varieties of crystal surface is very common, such as the Green Ghost, hair crystal and so on.

Crystal has always been considered to have a spiritual, magnetic field of the mysterious gem variety, people for crystal products love is unique, but also because of this, derived a variety of crystal imitations.

Synthetic crystals are in the ideal environment of artificial control, the crystal crystals, which are cultured in the natural environment, grow about 0.8 millimeters per day. After cutting, as a chip for electronic, computer, communication industry used synthetic crystal thickness of about 3 centimeters, it takes about 40 days to grow; to make a crystal ball of 10 centimeters (100mm) or more in the jewellery industry, it usually takes about 120-180 days in the ideal environment. Synthetic crystal chemical composition, molecular structure, optical properties, mechanical, electrical properties and natural crystal exactly the same, and more pure than natural crystal crystals, almost no impurities, color is better. In the process of discriminant analysis, it can be distinguished from synthetic crystals by observing the internal inclusions and growth patterns of natural crystals.

Molten crystal is the natural crystal waste produced after cutting in the high temperature and pressure smelting recrystallization formed, itself does not have crystal characteristics, through the crystal of the mineral characteristics can be distinguished. Molten crystal with high temperature resistance, can be made into crystal cups, tea sets and other practical products.

Crystal "wins the Jade", "The ice clear", glittering and translucent transparent, is the gem family's indispensable scenery, through to the natural Crystal Appraisal analysis and the crystal imitation Comparison analysis, may distinguish them.

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