考研英語作文：Topaz
在學習、工作乃至生活中，大家一定都接觸過作文吧，作文是從內部言語向外部言語的過渡，即從經過壓縮的簡要的`、自己能明白的語言，向開展的、具有規范語法結構的、能為他人所理解的外部語言形式的轉化。你知道作文怎樣才能寫的好嗎？下面是小編整理的考研英語作文：Topaz，希望能夠幫助到大家。
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 worlds 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.
【考研英語作文：Topaz】相關文章：
考研英語作文02-23
英語考研作文02-15
考研英語作文12-01
考研英語作文精選01-25
考研英語作文精選11-07
考研英語作文08-05
考研英語07-26
考研英語作文范文07-31
考研英語作文模板01-15
考研英語作文方法12-28