英語聽力文摘664 白金為何是白色的
- 聽力原文
- 參考譯文
Many people associate the metal gold with the color gold. But, some gold jewelry is not golden at all: it’s white.
Golden Color
Gold is one of the heaviest and softest metals. Pure gold, called 24-carat gold, is so soft that it can be easily dented. In the movies, old-time prospectors bite on yellow nuggets to see if they’re real gold because 24-carat gold will show a bite mark. In the real world, jewelers don’t want to use metal that can be dented so easily. So, most jewelry is actually an alloy of gold with harder metals.
Since pure gold is called 24-carat gold, an alloy of half gold and half other metals is called 12 carat gold, because, well, 12 is half of 24.
Alloys
If most gold jewelry is an alloy, why is some white and some yellow? The final appearance depends on the type of alloy metal used. Alloys made with white metals like silver, palladium and nickel create white-colored gold. Adding some copper to the alloy will restore the yellow color, but too much copper can turn the gold reddish.
The color of gold jewelry doesn’t reveal how much gold is in it — a piece of white gold may have the same number of carats as a piece of yellow gold. But, it has a different alloy metal, and so it has a different color.
Unlike white gold, fool’s gold has no gold in it at all. It’s a mineral called iron pyrite. Black gold isn’t gold either, it’s oil. Which is also valuable, but doesn’t look as good on your fiancée’s finger.
白金為何是白色的?
很多人都認為金子就應(yīng)該是金色。但一些黃金首飾的顏色并不是金色，而是白色。
金色
黃金是最重最軟的金屬之一。純金，也就是24k金質(zhì)地非常軟，很容易產(chǎn)生凹陷。在電影中，以前的勘探者通常會咬一咬黃金來看看是否是真金，這是因為你在24k金上會發(fā)現(xiàn)咬痕。然而，在現(xiàn)實世界中，珠寶商并不希望使用那種易產(chǎn)生凹陷的金屬。因此，大多數(shù)金屬實際上是黃金與其他硬金屬鑄成的合金。
由于純金被叫做24k金，那么由黃金和其他金屬各半鑄成的合金就叫做12k金，因為12是24的一半。
合金
如果大多數(shù)黃金首飾是合金的話，為什么有的是白色有的是黃色呢?珠寶最終的顏色還要取決于所使用合金金屬的類型。用白色金屬，如銀、鈀和鎳制成的合金就是白色的黃金。在合金中融入銅可以恢復(fù)成黃色，但是如果加入過多銅就會使黃金變紅。
黃金首飾的顏色并不能說明含金量。一塊白金的含金量可能與一塊黃金的含金量相同。但由于黃金里摻有不同的合金金屬，因此黃金可以呈現(xiàn)出不同的顏色。
與白金不同的是，愚人金不含任何黃金。它其實是一種叫做黃鐵礦的物質(zhì)。黑金也不是黃金，而是石油。黑金同樣很值錢，但是戴在你未婚妻手指上可不那么好看。
