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氧化铝、刚玉、红宝石和蓝宝石虽然名称各异,其形态、硬度、性质、用途也不相同,贵贱更是相距甚远,但是它们的化学成份却完全相同,皆是氧化铝. 一.氧化铝 纯净的氧化铝是白色无定形粉末,俗称矾土,密度9-0g/cm3,熔点2050℃、沸点2980℃,不溶于水,氧化铝主要有α型和γ型两种变体,工业上可从铝土矿中提取. 铝土矿(Al2O3·H2O和Al2O3·3H2O)是铝在自然界存在的主要矿物,将其粉碎后用高温氢氧化钠溶液浸渍,获得铝酸钠溶液;过滤去掉残渣,将滤液降温并加入氢氧化铝晶体,经长时间搅拌,铝酸钠溶液会分解析出氢氧化铝沉淀;将沉淀分离出来洗净,再在950-1200℃的温度下煅烧,就得到α型氧化铝粉末,母液可循环利用.此法由奥地利科学家拜耳(K.J.Bayer)在1888年发明,时至今日仍是工业生产氧化铝的主要方法,人称“拜耳法”. 在α型氧化铝的晶格中,氧离子为六方紧密堆积,Al3+对称地分布在氧离子围成的八面体配位中心,晶格能很大,故熔点、沸点很高.α型氧化铝不溶于水和酸,工业上也称铝氧,是制金属铝的基本原料;也用于制各种耐火砖、耐火坩埚、耐火管、耐高温实验仪器;还可作研磨剂、阻燃剂、填充料等;高纯的α型氧化铝还是生产人造刚玉、人造红宝石和蓝宝石的原料;还用于生产现代大规模集成电路的板基. γ型氧化铝是氢氧化铝在140-150℃的低温环境下脱水制得,工业上也叫活性氧化铝、铝胶.其结构中氧离子近似为立方面心紧密堆积,Al3+不规则地分布在由氧离子围成的八面体和四面体空隙之中.γ型氧化铝不溶于水,能溶于强酸或强碱溶液,将它加热至1200℃就全部转化为α型氧化铝.γ型氧化铝是一种多孔性物质,每克的内表面积高达数百平方米,活性高吸附能力强.工业品常为无色或微带粉红的圆柱型颗粒,耐压性好.在石油炼制和石油化工中是常用的吸附剂、催化剂和催化剂载体;在工业上是变压器油、透平油的脱酸剂,还用于色层分析;在实验室是中性强干燥剂,其干燥能力不亚于五氧化二磷,使用后在175℃以下加热6-8h还能再生重复使用. 目前世界上用拜耳法生产的氧化铝要占到总产量的90%以上,氧化铝大部分用于制金属铝,用作其它用途的不到10%. 二.刚玉 自然界天然存在的α型氧化铝晶体叫做刚玉,常因含有不同的杂质而呈现不同的颜色.刚玉一般呈带蓝或带黄的灰色,有玻璃或金刚光泽,密度在9-1g/cm3,硬度8,仅次于金刚石和碳化硅,能耐高温.含有铁的氧化物的刚玉砂叫金刚砂,呈暗灰色、暗黑色,常作研磨材料,用于制各种研磨纸、砂轮、研磨石,也用于加工光学仪器和某些金属制品. 因天然刚玉产量供不应求,工业上常将纯α型氧化铝粉末在高温电炉中烧结制成人造刚玉,也称电熔刚玉.它能耐1800℃以上的高温,是制造高级特殊耐火材料的原料,有高温下机械强度大,抗热震性好,抗侵蚀性强,热膨胀系数小等特点,用于制火箭发动机燃烧室内衬、喷咀,雷达天线保护罩,原子能反应堆材料,高级高频绝缘陶瓷,冶炼纯金属和合金的坩埚,高温发热原件,热电偶保护管,各种高温炉的炉衬等.人造刚玉还用于制精密仪表轴承和金属丝的拉丝模具.我国自1958年起就能产生人造刚玉了. 三.红宝石和蓝宝石 混有少量不同氧化物杂质的优质刚玉就是大名鼎鼎的红宝石和蓝宝石,是制作名贵首饰的材料,其微粒可制精密仪表和手表的轴承. 红宝石是天然产的透明红色刚玉,颜色从淡玫瑰红至深胭脂红,有的还略带紫色色调,有的有星光,以呈鸽子血红色最具有商业价值.红色是晶体中含少量氧化铬之故.红宝石是宝石中的珍品,七月生辰石.红宝石英语为Ruby,源出拉丁语ruber意为红色,硬度为9,密度常为4g/cm3,有金刚光泽.天然红宝石重量达1克拉的不多,超过5克拉已属罕见,世界上每年开采的红宝石其中品质最优者仅占千分之一.世界天然红宝石迄今发现最大的重3450克拉产自缅甸,世界著名的巨大星光红宝石重7克拉,著名的鸽血红宝石重55克拉.世界红宝石最有名的产地是缅甸曼德拉的东北部,还有泰国、斯里兰卡、柬埔寨.1973年在非洲肯尼亚的恩干加,1978年在澳大利亚中部阿利斯波利,70年代末在巴基斯担的罕萨先后发现大型红宝石矿藏,以上发现被誉为70年代世界红宝石矿三大发现.我国红宝石主要产地为云南

关于宝石的论文题目大全高中英语

354 评论(13)

sheeniya

相似宝玉石的常规仪器鉴定摘要:笔者对相似宝玉石进行了论述,重点叙述了28种相似宝玉石品种的鉴别与相似宝玉石品种的区别特征。关键字:相似宝玉石鉴定特征区别 1、钻石与合成碳硅石的鉴别二者在光泽、火彩、密度上基本相同,折射率都大于78,用热导仪检测均有钻石反应。所不同的是:合成碳硅石为一轴晶正光性,放大观察时小面棱重影、白线状细长的管状包体,在电导仪下具导电反应;而钻石放大观察无小面棱重影,且具有天然矿物包体,电导仪检测无反应。2、红宝石与红色石榴子石的鉴别二者均为红色、光泽、密度又相似;红宝石为非均质体宝石,具多色性。石榴子石为均质体宝石,无多色性;前者有荧光。后者无;前者的光谱在蓝区为吸收线。后者的光谱在蓝区为吸收带;3、紫水晶、方柱石、堇青石的鉴别三者均为紫色调,折射率、密度基本相似。紫水晶与方柱石的区别在于:前者无解理,贝壳状断囗,有色带,一轴晶正光性。而后者具有解理,参差状断囗,一轴晶负光性;紫水晶与堇青石的区别:堇青石有解理,二轴晶,三色性明显。而紫水晶为弱二色性;堇青石与方柱石的区别:前者明显的三色性,二轴晶。后者弱的二色性,一轴晶;4、碧玺、磷灰石、赛黄晶的鉴别三者虽然颜色各异,但其折射率、密度基本相似。其主要区别在于:碧玺为一轴晶负光性,双折射率大,具明显的二色性,放大观察可见明显的小面棱重影;磷灰石也为一轴晶负光性,但双折射率小,多色性不明显,具解理,在580nm有双吸收线;赛黄晶虽然具解理,但为二轴晶,可见干涉图和弱的荧光;5、石英与长石的鉴别这里的石英是指具有乳光效应、半透明的种类。长石是指具有月光效应的白色品种;二者的区别在于:石英为一轴晶正光性,无解理、贝壳状断囗,折射率为544—553;长石为二轴晶,有解理、具晕彩效应;6、尖晶石与符山石的鉴别尖晶石与符山石的区别:前者均质性,有时具光性异常,无多色性,放大观察见细小八面体负晶;后者为一轴晶,有多色性,但是双折射率小,放大观察见气液包体、矿物包体;7、透辉石与矽线石的鉴别透辉石的鉴定特征为具有两组解理,断囗为参差状,外光源放大观察(凸面型的底面),除了具明显的阶梯状断面外,还有与之垂直的裂缝,此裂缝即为另一组解理,多具星光效应;与之区别的矽线石特征为:具有一组解理,外光源放大观察(凸面型的底面),具有向珍珠的沙丘纹状的阶梯,实为解理,没有与之垂直的裂缝,此为一组解理的特征,多具有星光效应;8、绿色柱晶石与绿色透辉石的鉴别二者均为二轴晶,也都具猫眼效应。区别在于:柱晶石具明显的多色性,双折射率小。而透辉石具有弱的多色性,双折射率较大,铬透辉石在红区有铬的吸收线;9、无色钠长石玉、无色石英岩玉、无色蛇纹石玉、无色玛瑙的鉴别无色钠长石玉主要由钠长石组成,其折射率均低于54,放大观察(凸面型的边部),多数具柱粒状变晶结构;而石英岩玉的折射率为54以上,放大观察(凸面型的边部)为鳞片粒状或粒状变晶结构。也就是二者的折射率、结构不一样;无色蛇纹石玉为纤维状变晶结构,区别于石英岩玉、钠长石玉;而玛瑙为隐晶质结构,具同心层状、条带状组构。区别于其它玉石;10、葡萄石与软玉的鉴别葡萄石除可见到特征的放射状结构外,亦可见438nm的弱吸收带。此带位于紫区的边缘,在观察时,必须先观察分光镜紫区的宽窄,然后放上宝石观察才能观察到;软玉为纤维状变晶结构,分光镜检测,各别在蓝区有模糊的吸收线,紫区无;11、翡翠与水钙铝榴石的鉴别此二种玉石只是密度相似,折射率相差较大,二者的结构也有差别,之所以在这里提出,是因为在平时的教学中,学生常把水钙铝榴石鉴定为染色的翡翠。究其原因是学生只观测了滤色镜和密度,而没有测折射率。故二者的区别是:结构、折射率;12、菱锰矿与蔷薇辉石的鉴别二者均为锰至色,又都为粉红色。区别在于:前者的折射率在60-78之间变化,是一个动值。而后者的折射率在73左右,是一个固定的值(54除外,因测到共生物石英);前者的组构为鲕状、肾状、条带状、层纹状、粒状等。而后者为柱粒状变晶结构;前者盐酸测试有反应,后者无反应;以上是笔者在多年的教学实践中总结出来的一些经验,由于样品所限,难免有挂一漏万之嫌。故只能是抛砖引玉,以此启发、告诫同行和后人,少走或不走弯路。因为在宝玉石的鉴定过程中,要有科学的态度,严紧求实的作风。切不可对所从事的工作不负责任,我们鉴定工作者的失误,会给消费者和商家带来不必要的麻烦、社会的不和协、经济上的纠纷等,为此宝玉石鉴定是一项科学性和技术性很强的工作,必须严格地按照工作程序有步骤和有条理的进行,而不应敷衍塞责、信口开河、应付了事。宝玉石鉴定的结果应该是准确无误,即使经权威的宝玉石鉴定专家运用现代的仪器设备进行核查也仍然如此。以树立良好的信誉。珠宝鉴定工作者必须具有强烈的事业心、有为国家和社会、为人民负责任的精神,愿意为宝玉石事业发展而努力工作,做诚实守信的模范。参考文献李劲松赵松龄等。宝玉石大典北京:北京出版社2001李兆聪宝石鉴定法北京地质出版社1994
257 评论(9)

默写这幸福

1、题目:题目应简洁、明确、有概括性,字数不宜超过20个字(不同院校可能要求不同)。本专科毕业论文一般无需单独的题目页,硕博士毕业论文一般需要单独的题目页,展示院校、指导教师、答辩时间等信息。英文部分一般需要使用Times NewRoman字体。2、版权声明:一般而言,硕士与博士研究生毕业论文内均需在正文前附版权声明,独立成页。个别本科毕业论文也有此项。3、摘要:要有高度的概括力,语言精练、明确,中文摘要约100—200字(不同院校可能要求不同)。4、关键词:从论文标题或正文中挑选3~5个(不同院校可能要求不同)最能表达主要内容的词作为关键词。关键词之间需要用分号或逗号分开。5、目录:写出目录,标明页码。正文各一级二级标题(根据实际情况,也可以标注更低级标题)、参考文献、附录、致谢等。6、正文:专科毕业论文正文字数一般应在3000字以上,本科文学学士毕业论文通常要求8000字以上,硕士论文可能要求在3万字以上(不同院校可能要求不同)。毕业论文正文:包括前言、本论、结论三个部分。前言(引言)是论文的开头部分,主要说明论文写作的目的、现实意义、对所研究问题的认识,并提出论文的中心论点等。前言要写得简明扼要,篇幅不要太长。本论是毕业论文的主体,包括研究内容与方法、实验材料、实验结果与分析(讨论)等。在本部分要运用各方面的研究方法和实验结果,分析问题,论证观点,尽量反映出自己的科研能力和学术水平。结论是毕业论文的收尾部分,是围绕本论所作的结束语。其基本的要点就是总结全文,加深题意。7、致谢:简述自己通过做毕业论文的体会,并应对指导教师和协助完成论文的有关人员表示谢意。8、参考文献:在毕业论文末尾要列出在论文中参考过的所有专著、论文及其他资料,所列参考文献可以按文中参考或引证的先后顺序排列,也可以按照音序排列(正文中则采用相应的哈佛式参考文献标注而不出现序号)。9、注释:在论文写作过程中,有些问题需要在正文之外加以阐述和说明。10、附录:对于一些不宜放在正文中,但有参考价值的内容,可编入附录中。有时也常将个人简介附于文后。
238 评论(14)

野草lyx

Gemstones have played an important role in the religious and secular life of India from very early They were used in sacred ceremonies as magical charms and for protection against all forms of evil besides being decorative or luxury They were also considered to have invaluable healing Their worth was equally tied to their spiritual qualities, their aesthetic appeal, their monetary value and their supernatural The Legend According to a legend, a powerful demon Bala conquered the kingdom of Heaven and became a tyrannical ruler of the The demi-gods, however, opposed his rule and sought to destroy Under the pretext of choosing a boon, they requested Bala to be the sacrificial animal in a ritual Once the demon was tied to the stake, the demi-gods killed His body was dismembered and the severed parts of his body were transformed into precious gem Then followed a great tussle among the demi-gods and other celestial beings over the As a result, these got Some fell into rivers, some in oceans and others into forests and As they lay buried, they began to germinate into rubies, sapphires, cat's eyes, and an endless variety of other precious On account of their intrinsic merit, some of them imbibed the power of quelling obstacles accruing from the influence of demons, poisons, serpents and sickness whereas others were devoid of any Types Of Gems As Described In PuranasVarious types of gems figure in the Puranas (ancient Sanskrit texts) and each of them is associated with specific Works on Indian chemistry proclaim nine varieties of gems: diamond, coral, pearl, emerald, cat's eye, cinnamon stone (gomedaka), ruby, sapphire and The Puranas also refer to lapis lazuli and Modern gemologists believe that, except for the emerald, all these precious stones were mined in I The known emerald mines of this country are of modern No evidence of ancient emerald mines has been found in I It is probably that emeralds used in ancient jewelry were stones that found their way into India from ancient E In Egypt, emerald mines and working tools and other equipment dating to about 1650 BC have been The science of gem preparation in ancient India was well developed in the early centuries of the Christian era (Puranic perioid) The diamond was found in different parts of the country and at least six colors of diamonds were known, each being associated with a particular deity: green with Vishnu (the Preserver), white with Varuna (god of Oceans), yellow with Indra (god of Heavens), brown with Agni (Fire god), blue with Yama (god of Death) and copper colored with the Maruts (Storm god) A Diamond For Each CasteThe king could wear diamonds of any color, as he was the lord of all Each caste, however, was recommended a specific color and improper use of colors in diamonds by the different castes was believed to be the most Thus, for a Brahmin (the priestly class) a diamond of pure white luster was For a Kshatriya (warrior class), a diamond of a reddish hue was considered auspicious, for a Vaisya (trading class) one with a greenish tint was appropriate and for the Sudra (working class) one, which had the luster of a well-polished sword, was believed to be A spotless diamond was considered to be the abode of A perfect diamond was considered to be the one that could float in water and had six elevated tips, eight equal sides and twelve sharp World's Greatest DiamondsSome of the world's greatest diamonds have originated in India such as the Kohinoor, the Great Mogul and O The Kohinoor, which after changing hands many times, was purchased by Britain in 1849 and now adorns the crown of the Queen of E Originally, it weighed 191 carats but when it was recut in 1852 at Garrards of London its weight was reduce to 108 The Great Mogul found in 1650 weighed 280 It was the largest diamond ever cut in India and its whereabouts are The Orlov, which had its origin in the mid-18th century Karnataka war, was stolen from an Indian temple where it formed one of the eyes of an It weighed nearly 200 carats and was sold to an English naval It was eventually bought by Russian Court and now adorns the Kremlin Testing The StonesThere are references in ancient Indian texts about the preparation of imitation diamonds by the use of iron, topaz, gomedaka, lapis lazuli, crystal and different kinds of And that is perhaps why diamonds were tested by means of alkaline solutions and the emery According to the Garuda Purana, to test whether a pearl is real or not, it should be placed in heated water mixed with some oil and salt, for one After removing it from the water, it should be rubbed with barley grains and then covered with a dry If it does not lose its luster then it is a real Methods for giving luster to a pearl are also The pearl should be placed in cavity of a fish, which is then smeared with clay and The pearl should then be boiled in milk, then in water and finally in The pearl thus treated assumes an excellent Effect On Human BodyAccording to the traditional Indian belief, the human body is composed of the seven colors of the rainbow, associated with seven kinds of Diseases enter the body when there is a deficiency or excess of any ray in our Each color is associated with a particular gem, which in turn is associated with a particular According to astrologers, a gem is beneficial when worn in the phase of a particular planet as these stones also affect our health and Besides, there are other important characteristics of gemstones in their medicinal The ruby associated with the Sun is extremely hot and releases hot waves in the form of red cosmic It should be worn only during the winter It cures ulcers, bone disorders, arthritis, blood diseases, anemia and general The pearl is associated with the Moon, which in turn is associated with fertility and Being cold, it releases cold waves capable of curing diseases arising out of hot rays - heat stroke, high blood pressure, boils and It is particularly useful for uterine The red coral is associated with Mars and is a very useful gem for every It rules over the excretory glands, kidney, urinary systems, sex organs and sweat By assuring the proper clearing out of waste products from the blood and body, it keeps the body The emerald is associated with Mercury, the planet of nerves, intellect, memory, creative ability and This gem has the power to cure all sorts of eye and ear troubles, forgetfulness, epilepsy, stammering, insanity and nervous Real emeralds can be determined by holding them for some times before the A fake stone will impart a hot or irritable sensation to the But a real emerald will soon make the eyes The blue sapphire is associated with Saturn and is believed to have miraculous and magical powers in healing all sorts of diseases of the brain and The very light blue sapphire is usually preferred for healing It cures diarrhea, dysentery, gastric ulcers, nervous disorders, heart troubles, paralysis, Parkinson's diseases, arthritis and But it is too cold and should be worn on the middle finger of the right hand along with a copper ring on the first finger of the left The copper ring will protect the wearer from the bad effects of the blue This stone strengthens concentration, precision and perfection in any During the winter months the sapphire should be worn with a red coral otherwise, there is a possibility that one will have to suffer from severe cold, cough, bronchitis and The cat's eye associated with Ketu is an extremely hot gem and heals cancer, paralysis, acne and other skin The yellow sapphire (topaz) is associated with Jupiter and is believed to have the miraculous power to bring prosperity and It cures rheumatism, arthritis, gout, sciatica, lumbago, spondylitis, impotency, frigidity and It is preferably used with one red The diamond is neither hot nor It is associated with Venus and is believed to have no real power in healing any Today, gems have increasingly acquired a commercial And given the rich tradition our society is steeped in, gems will continue to be an important part of our religious and secular Healing PropertiesEach gem in the mala was given certain attributes of healing properties, according to ancient lore, and the practice is still in vogue The ruby protects against poisonous substances and banishes any evil spirits that hover It also gives energy to the wearer and changes color if the wearer is in bad The emerald is an antidote for all stomach complaints, stings and bites; it is soothing to eyes when mixed with saffron, and a protection against poisonous insects or It was used in ancient times by mariners to prevent Emeralds are said to pale if the wearer is faced with As it is the stone of the Goddess of Love, it helps lovers in their The coral is extremely popular as it is a stone that is said to cure diseases, help the memory and act as a powerful protection against the That is perhaps why it is often used in rosaries and made into chains for little Pearls give strength to the heart and are often used in Ayurvedic In India, pearls have always been a favorite ornament in royal Blue has always been the color of enlightenment and in Buddhism, the wearing of sapphire was said to increase In the West, bishops and cardinals also wore sapphires in ancient In spite of being held in sacred esteem, sapphires can also bring bad luck if worn by a person who does not have it as a The garnet is found in many colors though the best known is deep red, almost resembling a Garnets are often used to imitate precious stones, but have not been recorded as having any special properties of On the other hand, the topaz is used for occult It is used in the Middle East, for averting the evil, and is said to bring wealth and long life to the The topaz can be golden yellow in color and sometimes The cat's eye is usually brownish There is often a light line, which shines through, giving the idea of an eye from which it derives its Many of these jewels are worn set in rings, mounted so that they touch the The stone and its weight are decided according to the individual's astrological The nine jewels of the necklace are a combination of the different gems and perhaps were originally threaded together to ensure general well There is no doubt that the variety of color looks beautiful and it would be interesting if more research were done in the meaningfulness of the Navaratna, the nine
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