新东方背诵文选 L38 Topaz

Topaz is a hard, transparent¹ mineral. It is a compound of aluminum², silica, and fluorine. Gem³ topaz is valuable. Jewelers call this variety of the stone "precious topaz". The best-known precious topaz gems⁴ 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 quartz⁵.
The golden variety of precious topaz is quite uncommon⁶. 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 determined⁷ 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 plentiful⁸ than true topaz. Most of it is variety of amethyst⁹: that heat has turned brown.
[ NOTE] : topaz / 'tэupжz; `topжz/ n (a) [U] transparent yellow mineral 黄玉（矿 物）. (b) [C] semi-precious gem cut from this 黄玉; 黄宝石.

1 transparent   

adj.明显的，无疑的；透明的

参考例句：

• The water is so transparent that we can see the fishes swimming.水清澈透明，可以看到鱼儿游来游去。
• The window glass is transparent.窗玻璃是透明的。

2 aluminum   

n.(aluminium)铝

参考例句：

• The aluminum sheets cannot be too much thicker than 0.04 inches.铝板厚度不能超过0.04英寸。
• During the launch phase,it would ride in a protective aluminum shell.在发射阶段，它盛在一只保护的铝壳里。

3 gem   

n.宝石，珠宝；受爱戴的人 [同]jewel

参考例句：

• The gem is beyond my pocket.这颗宝石我可买不起。
• The little gem is worth two thousand dollars.这块小宝石价值两千美元。

4 gems   

growth； economy； management； and customer satisfaction 增长

参考例句：

• a crown studded with gems 镶有宝石的皇冠
• The apt citations and poetic gems have adorned his speeches. 贴切的引语和珠玑般的诗句为他的演说词增添文采。

5 quartz   

n.石英

参考例句：

• There is a great deal quartz in those mountains.那些山里蕴藏着大量石英。
• The quartz watch keeps good time.石英表走时准。

6 uncommon   

adj.罕见的，非凡的，不平常的

参考例句：

• Such attitudes were not at all uncommon thirty years ago.这些看法在30年前很常见。
• Phil has uncommon intelligence.菲尔智力超群。

7 determined   

adj.坚定的；有决心的

参考例句：

• I have determined on going to Tibet after graduation.我已决定毕业后去西藏。
• He determined to view the rooms behind the office.他决定查看一下办公室后面的房间。

8 plentiful   

adj.富裕的，丰富的

参考例句：

• Their family has a plentiful harvest this year.他们家今年又丰收了。
• Rainfall is plentiful in the area.这个地区雨量充足。

9 amethyst   

n.紫水晶

参考例句：

• She pinned a large amethyst brooch to her lapel.她在翻领上别了一枚大大的紫水晶饰针。
• The exquisite flowers come alive in shades of amethyst.那些漂亮的花儿在紫水晶的映衬下显得格外夺目。