●首页 加入收藏 网站地图 热点专题 网站搜索 [RSS订阅] [WAP访问]  
语言选择:
英语联盟 | www.enun.cn
英语学习 | 英语阅读 | 英语写作 | 英语听力 | 英语语法 | 综合口语 | 考试大全 | 英语四六 | 英语课堂 | 广播英语 | 行业英语 | 出国留学
品牌英语 | 实用英语 | 英文歌曲 | 影视英语 | 幽默笑话 | 英语游戏 | 儿童英语 | 英语翻译 | 英语讲演 | 求职简历 | 奥运英语 | 英文祝福
背景:#EDF0F5 #FAFBE6 #FFF2E2 #FDE6E0 #F3FFE1 #DAFAF3 #EAEAEF 默认  
阅读内容

新概念优美背诵短文50篇 Unit38:Topaz

[日期:2008-01-28]   [字体: ]
38 Topaz
Topaz is a hard, transparent mineral. It is a compound of aluminum, silica, and fluorine. Gem topaz is valuable. Jewelers call this variety of the stone “precious topaz”. The best-known precious topaz gems range in color from rich yellow to light brown or pinkish red. Topaz is one of the hardest gem minerals. In the mineral table of hardness, it has a rating of 8, which means that a knife cannot cut it, and that topaz will scratch quartz.
The golden variety of precious topaz is quite uncommon. Most of the world’s topaz is white or blue. The white and blue crystals of topaz are large, often weighing thousands of carats. For this reason, the value of topaz does not depend so much on its size as it does with diamonds and many other precious stones, where the value increases about four times with each doubling of weight. The value of a topaz is largely determined by its quality. But color is also important: blue topaz, for instance, is often irradiated to deepen and improve its color.
Blue topaz is often sold as aquamarine and a variety of brown quartz is widely sold as topaz. The quartz is much less brilliant and more plentiful than true topaz. Most of it is variety of amethyst: that heat has turned brown.

黄水晶
黄水晶是一种坚硬、透明的矿物质。它是铝、硅和氟的化合物。黄水晶宝石价值不菲。珠宝商把这种石头称为"黄玉"。
最出名的黄玉有各种颜色如深黄色、淡棕色、浅红色等。黄水晶是最坚硬的宝石矿中的一种。在矿石硬度表上,它的硬度为8,这表明刀子不能割开
它而它可在石英上划痕。金黄色的黄玉品种非常罕见。世界上大多数的黄水晶是白色或蓝色的。这些白色或蓝色的黄水晶晶体很大,常常有数千克拉重。
由于这个原因,黄水晶的价值不像钻石和许多其它宝石那样主要依赖于其大小,重量翻一番价值即上升约四倍。黄
水晶的价值很大程度上取决于其品质,但颜色也很重要。举例来说,蓝色的黄水晶常需放射处理以加深和改善其颜色。
蓝色的黄水晶常被作为海蓝宝石出售,许多种棕色石英被当作黄水晶广为贩卖。石英光亮度远小于黄水晶,矿藏储量也远较黄水晶丰富。大多数石英
是一种紫水晶,高温使其变为棕色。
 
 
   免责声明:本站信息仅供参考,版权和著作权归原作者所有! 如果您(作者)发现侵犯您的权益,请与我们联系:QQ-50662607,本站将立即删除!
 
阅读:

推荐 】 【 打印
相关新闻      
本文评论       全部评论
发表评论

点评: 字数
姓名:
内容查询

热门专题
 图片新闻