Amethyst

紫水晶

These samples of amethyst are displayed in the Smithsonian Museum of Natural History. Amethyst is a variety of quartz with the characteristic composition SiO₂, but distinctive and popular for its dramatic purple color. The sample at left is from Upper Providence, Pennsylvania and is about 10x8 cm. The gem is 36.2 carats.

这些紫水晶样本陈列在史密森尼自然历史博物馆中。紫水晶是二氧化硅的一种变种，具有特征性组成SiO₂，但因其鲜明的紫色而独具特色且广受欢迎。左侧样本来自宾夕法尼亚州上普罗维登斯，尺寸约为10x8厘米，宝石重36.2克拉。

"Quartz will commonly contain trace amounts of iron ( in the range of 10's to 100's parts per million of iron). The color in amethyst comes from color centers in the quartz. These are created when trace amounts of iron are irradiated ( from the natural radiation in the rocks)." (Minsocam)

石英通常含有微量的铁（铁的含量在百万分之十到一百之间）。紫水晶的颜色来自石英中的色心。这些色心是在微量铁被辐射（来自岩石中的天然辐射）后形成的。

This dramatic amethyst-lined tube has front dimensions of about 35x30 cm and the displayed section is about a meter long!

这种饰有紫罗兰色玻璃的管子长度约为35厘米×30厘米，展示部分约有一米长！

" Some of this iron sits in sites normally occupied by silicon and some is interstitial ( in sites where there is normally not an atom). The iron is usually in the +3 valence state. Gamma ray radiation ( from nuclear decay in the surrounding rocks ) can knock an electron from an iron lattice site and deposit the electron in an interstitial iron. This +4 iron absorbs certain wavelengths (357 and 545 nanometers) of light causing the amethyst color. You need to have quartz that contains the right amounts of iron and then is subjected to enough natural radiation to cause the color centers to form." (Minsocam)

其中一些铁原子占据着本应由硅原子占据的位点，另一部分则位于间隙位点（即本应没有原子的位置）。铁通常处于+3价状态。伽马射线辐射（来自周围岩石的核衰变）可以将一个电子从铁的晶格位点敲出，并将该电子沉积到间隙铁位点中。这种+4价的铁会吸收特定波长（357和545纳米）的光，从而产生紫水晶的颜色。你需要有含有适当铁含量的石英，并且使其受到足够的天然辐射，以促使色心形成。

The amethyst sample at left above is about 8x8 cm and is from Las Vigas, Vera Cruz, Mexico. The gems are 204.1 and 72.2 carats and are from Rio Grande do Sul, Brazil.

上图左侧的紫水晶样品尺寸约为8x8厘米，来自墨西哥韦拉克鲁斯州拉斯维加斯。宝石的重量分别为204.1和72.2克拉，来自巴西南里奥大河州。

At left is amethyst formed on smoky quartz from Pondorf mine, Jefferson County, Montana. That sample is about 6x9 cm. The sample at right is about 10x20cm from Due West, South Carolina.

左侧是来自蒙大拿州杰斐逊县庞多尔矿的烟 quartz 形成的紫水晶，尺寸约为6x9厘米。右侧样本来自南卡罗来纳州杜威西，尺寸约为10x20厘米。

The amethyst gems at left are 41.2 and 61.4 carats and are from Brazil. The center pair of gems are 44.5 and 33.2 carats and are from Alexander County, North Carolina. The right pair are 109.6 and 163.8 carats and are from Rio Grande do Sul, Brazil.

左边的紫水晶宝石分别为41.2和61.4克拉，来自巴西。中间的两颗宝石为44.5和33.2克拉，来自北卡罗来纳州亚历山德里亚县。右边的两颗宝石分别为109.6和163.8克拉，来自巴西的里奥格兰德-do-.sul州。

At left is an amethyst crystal formation about 4x5 cm from Virginia. The sample at right is about 5x17 cm and is from Cripple Creek, Colorado.

左侧是一块来自弗吉尼亚的紫水晶晶体，尺寸约为4x5厘米。右侧的样品尺寸约为5x17厘米，来自科罗拉多州的Cripple Creek。

This amehtyst sample shows the form known as scepter crystals. It is from Hopkinton, Rhode Island. The size is about 30 cm across.

这种铵石样本呈现出一种称为权杖晶体的形态。它来自罗德岛的霍普金顿。尺寸大约是30厘米。

This amehtyst sample is from Rio Grande do Sul, Brazil. The size is about 35 cm across.

这块铵石样本来自巴西的圣卢卡斯州，尺寸约为35厘米。