iridium

Analyzing the fossils at this small site, they counted 52 distinct species just below the iridium layer..他们分析了这个小地区的化石层，一共计算了在铱层下面的52个不同物种。

This story, though, raises the question of why there is but a single ejecta layer of iridium and shocked quartz in late Cretaceous rocks around the world..不过，这一假设提出了个问题，在全球各地白垩纪晚期岩石中，只有单独的一层铱和冲击石英，这是为什么？

In a laboratory vault outside Paris is a small cylinder of platinum–iridium alloy that serves as the standard for all mass measurements worldwide..在巴黎郊外的一个实验室地下室中，有一个铂铱合金作的圆筒，这个圆筒就是作为世界上所有质量测量的标准。