38 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.
黃水晶黃水晶是一種堅(jiān)硬、透明的礦物質(zhì)。它是鋁、硅和氟的化合物。黃水晶寶石價(jià)值不菲。珠寶商把這種石頭稱為"黃玉"。
最出名的黃玉有各種顏色如深黃色、淡棕色、淺紅色等。黃水晶是最堅(jiān)硬的寶石礦中的一種。在礦石硬度表上，它的硬度為8，這表明刀子不能割開它而它可在石英上劃痕。金黃色的黃玉品種非常罕見。世界上大多數(shù)的黃水晶是白色或藍(lán)色的。這些白色或藍(lán)色的黃水晶晶體很大，常常有數(shù)千克拉重。
由于這個(gè)原因，黃水晶的價(jià)值不像鉆石和許多其它寶石那樣主要依賴于其大小，重量翻一番價(jià)值即上升約四倍。黃水晶的價(jià)值很大程度上取決于其品質(zhì)，但顏色也很重要。舉例來說，藍(lán)色的黃水晶常需放射處理以加深和改善其顏色。
藍(lán)色的黃水晶常被作為海藍(lán)寶石出售，許多種棕色石英被當(dāng)作黃水晶廣為販賣。石英光亮度遠(yuǎn)小于黃水晶，礦藏儲(chǔ)量也遠(yuǎn)較黃水晶豐富。大多數(shù)石英是一種紫水晶，高溫使其變?yōu)樽厣?BR> 1 transparent
adj.明顯的，無疑的；透明的
參考例句：
The water is so transparent that we can see the fishes swimming.水清澈透明，可以看到魚兒游來游去。
The window glass is transparent.窗玻璃是透明的。
2 aluminum
n.(aluminium)鋁
參考例句：
The aluminum sheets cannot be too much thicker than 0.04 inches.鋁板厚度不能超過0.04英寸。
During the launch phase,it would ride in a protective aluminum shell.在發(fā)射階段，它盛在一只保護(hù)的鋁殼里。
3 gem n.寶石，珠寶；受愛戴的人 [同]jewel
參考例句：
The gem is beyond my pocket.這顆寶石我可買不起。
The little gem is worth two thousand dollars.這塊小寶石價(jià)值兩千美元。
4 gems
growth； economy； management； and customer satisfaction 增長
參考例句：
a crown studded with gems 鑲有寶石的皇冠
The apt citations and poetic gems have adorned his speeches. 貼切的引語和珠璣般的詩句為他的演說詞增添文采。
5 quartz
n.石英
參考例句：
There is a great deal quartz in those mountains.那些山里蘊(yùn)藏著大量石英。
The quartz watch keeps good time.石英表走時(shí)準(zhǔn)。
6 uncommon
adj.罕見的，非凡的，不平常的
參考例句：
Such attitudes were not at all uncommon thirty years ago.這些看法在30年前很常見。
Phil has uncommon intelligence.菲爾智力超群。
7 determined adj.堅(jiān)定的；有決心的
參考例句：
I have determined on going to Tibet after graduation.我已決定畢業(yè)后去西藏。
He determined to view the rooms behind the office.他決定查看一下辦公室后面的房間。
8 plentiful
adj.富裕的，豐富的
參考例句：
Their family has a plentiful harvest this year.他們家今年又豐收了。
Rainfall is plentiful in the area.這個(gè)地區(qū)雨量充足。
9 amethyst
n.紫水晶
參考例句：
She pinned a large amethyst brooch to her lapel.她在翻領(lǐng)上別了一枚大大的紫水晶飾針。
The exquisite flowers come alive in shades of amethyst.那些漂亮的花兒在紫水晶的映襯下顯得格外奪目。
黃水晶黃水晶是一種堅(jiān)硬、透明的礦物質(zhì)。它是鋁、硅和氟的化合物。黃水晶寶石價(jià)值不菲。珠寶商把這種石頭稱為"黃玉"。
最出名的黃玉有各種顏色如深黃色、淡棕色、淺紅色等。黃水晶是最堅(jiān)硬的寶石礦中的一種。在礦石硬度表上，它的硬度為8，這表明刀子不能割開它而它可在石英上劃痕。金黃色的黃玉品種非常罕見。世界上大多數(shù)的黃水晶是白色或藍(lán)色的。這些白色或藍(lán)色的黃水晶晶體很大，常常有數(shù)千克拉重。
由于這個(gè)原因，黃水晶的價(jià)值不像鉆石和許多其它寶石那樣主要依賴于其大小，重量翻一番價(jià)值即上升約四倍。黃水晶的價(jià)值很大程度上取決于其品質(zhì)，但顏色也很重要。舉例來說，藍(lán)色的黃水晶常需放射處理以加深和改善其顏色。
藍(lán)色的黃水晶常被作為海藍(lán)寶石出售，許多種棕色石英被當(dāng)作黃水晶廣為販賣。石英光亮度遠(yuǎn)小于黃水晶，礦藏儲(chǔ)量也遠(yuǎn)較黃水晶豐富。大多數(shù)石英是一種紫水晶，高溫使其變?yōu)樽厣?BR> 1 transparent
adj.明顯的，無疑的；透明的
參考例句：
The water is so transparent that we can see the fishes swimming.水清澈透明，可以看到魚兒游來游去。
The window glass is transparent.窗玻璃是透明的。
2 aluminum
n.(aluminium)鋁
參考例句：
The aluminum sheets cannot be too much thicker than 0.04 inches.鋁板厚度不能超過0.04英寸。
During the launch phase,it would ride in a protective aluminum shell.在發(fā)射階段，它盛在一只保護(hù)的鋁殼里。
3 gem n.寶石，珠寶；受愛戴的人 [同]jewel
參考例句：
The gem is beyond my pocket.這顆寶石我可買不起。
The little gem is worth two thousand dollars.這塊小寶石價(jià)值兩千美元。
4 gems
growth； economy； management； and customer satisfaction 增長
參考例句：
a crown studded with gems 鑲有寶石的皇冠
The apt citations and poetic gems have adorned his speeches. 貼切的引語和珠璣般的詩句為他的演說詞增添文采。
5 quartz
n.石英
參考例句：
There is a great deal quartz in those mountains.那些山里蘊(yùn)藏著大量石英。
The quartz watch keeps good time.石英表走時(shí)準(zhǔn)。
6 uncommon
adj.罕見的，非凡的，不平常的
參考例句：
Such attitudes were not at all uncommon thirty years ago.這些看法在30年前很常見。
Phil has uncommon intelligence.菲爾智力超群。
7 determined adj.堅(jiān)定的；有決心的
參考例句：
I have determined on going to Tibet after graduation.我已決定畢業(yè)后去西藏。
He determined to view the rooms behind the office.他決定查看一下辦公室后面的房間。
8 plentiful
adj.富裕的，豐富的
參考例句：
Their family has a plentiful harvest this year.他們家今年又豐收了。
Rainfall is plentiful in the area.這個(gè)地區(qū)雨量充足。
9 amethyst
n.紫水晶
參考例句：
She pinned a large amethyst brooch to her lapel.她在翻領(lǐng)上別了一枚大大的紫水晶飾針。
The exquisite flowers come alive in shades of amethyst.那些漂亮的花兒在紫水晶的映襯下顯得格外奪目。