比黄金还珍贵的颜料，到底是怎么消失的？

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Luxury blue paint pigment（颜料）
catalyses（催化） its own ‘disease’
奢侈的蓝色颜料催化自身的疾病

Prized for its deep blue colour and used in oil paintings since medieval times, ultramarine（群青色） can lose its bright colour and become ‘sick’. Now, researchers have found that this phenomenon（现象）, called ‘ultramarine disease’, is likely caused by catalytic（起催化作用的） activity of the pigment itself. The finding could aid（援助） conservation（保护） of renaissance（文艺复兴） artworks.
群青因深蓝色而备受青睐，自中世纪以来就用于油画中。但是，群青会随时时间流逝而失去其明亮的色彩，就像长病了一样。研究人员发现，这种被称为“群青综合症”的现象，很可能是由颜料本身的催化活性引起的。这一发现可以帮助保护文艺复兴时期的艺术品。
Ultramarine was traditionally produced by grinding（研磨） lapis lazuli（杂青金石） rock from mines in Afghanistan into a fine powder and blending it with oils and waxes（蜡）. It was the most expensive blue used by Renaissance painters and more precious（珍贵的） than gold. However, a synthetic（人造的） version was invented in 1826 making it far cheaper.