The colors of art change not just with trends， but availability as well. For reasons of being incredibly toxic3）， expensive， or just involving way too many snails， here are five pigments that have disappeared from art.

艺术作品的用色不仅会随着时尚潮流而改变，也会因是否有可用的颜料而改变。由于有剧毒或是过于昂贵，抑或仅仅是因为在制作过程中需要使用太多蜗牛，以下这五种颜料已经从艺术作品中绝迹了。

On murals4）， pottery， even possibly painted on the unlucky bodies offered as human sacrifices， a sky-blue color has been found in artifacts of the Maya and Aztec5）. It disappeared around colonial times in Central America， just like the pre-Columbian civilizations themselves. Known as Maya Blue， it's long been recognized as a mix of a natural clay and a dye from the indigo6） plant. But how it was so durable in not being subject to fading or even the deterioration of solvents7） and acids has been a mystery. Earlier in 2013， however， some chemists announced they may have found the secret.

The most prized pigment of the ancient world was actually made from a predatory9） snail. Tyrian Purple got its name from the best of the marine shellfish used to make the pigment being found off the shore of Tyre， according to Pigment Compendium10）. Not only was it a properly11） royal color of rich， slightly red purple， it was said to get even more beautiful and brighter when exposed to the sun and the elements12）. Yet since you needed a whole pile of snails to make it， it was very expensive， and eventually disappeared.

在玛雅人和阿兹特克人的古器物上可以看到一种天蓝色，比如在壁画和陶器上，甚至可能连用作人祭的那些可怜人的身体上也涂着这种颜色。和前哥伦布时期的那些美洲文明一样，大约在殖民时期，这种颜色也从中美洲消失了。这种被称为“玛雅蓝”的颜料长期以来一直被认为是用天然黏土和从槐蓝属植物中提取的染料混合而成的，但是它为什么如此耐久（既不容易褪色，甚至也不容易被溶剂和酸腐蚀）则一直是个谜。不过在2013年初，几位化学家宣称他们可能已经发现了其中的秘密。

这种古代世界最为珍贵的颜料其实是用一种肉食性蜗牛制作而成的。据《颜料手册》记载，推罗紫得名于一种上佳的海贝，它曾是制作这种颜料的原料，在推罗沿岸的海里可以觅得其踪影。这种紫中稍微透点红的浓郁色彩不仅非常高贵，而且据说在经过风吹日晒之后会变得更加美丽鲜艳。不过，制作这种颜料需要使用成堆的蜗牛，因此它十分昂贵，最后就消失了。

The luminosity13） of classical European oil paintings was due in large part to White Lead， a pigment of lead carbonate14） and sulfate15）. Artists like Vermeer used it to create a special kind of light that radiated16） from the canvas， the traces of which we can see in its grainy17） texture. Unfortunately， its striking brightness was rather poisonous. Yet as Applied Polymer18） Science explains about the lead paint： "Toxicity was recognized， but accepted." It's since been largely replaced by Titanium19） White， a less harmful pigment， yet some artists still seek out the White Lead for its superior color and permanence， even if it is more difficult to find and still toxic.

欧洲古典油画作品的那种光亮感在很大程度上都要归功于铅白——一种由碳酸铅和硫酸盐制成的颜料。诸如维米尔（编注：荷兰著名画家）之类的画家利用这种颜料创作出了一种从画布中发出的特殊亮光，我们可以从颜料粗糙的质感中看到这种亮光的痕迹。……