2019年12月大学英语六级第一套真题及答案:2019年12月大学英语六级阅读晨读美文：Topaz

【#四六级考试# 导语】英语四六级考试将要在2019年12月进行，日常的备考，听说读写都要关注，其中阅读理解是考生复习的重点和难点，日常备考需要加强英文阅读练习，下面是©文档大全网四六级频道为大家整理的《2019年12月大学英语六级阅读晨读美文：Topaz》一文，希望给大家带来帮助。

　　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 a variety of amethyst: that heat has turned brown.

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