Yesterday, we heard about the discovery in North Dakota of an astonishingly well-preserved leg of a dinosaur likely killed by the impact of the 12 kilometer-wide Chicxulub asteroid that crashed into the Gulf of Mexico 66 million years ago and eradicated 80% of Earth's animals. Meanwhile, scientists announced that they also found likely slivers of that asteroid at the same site, called Tanis. Kenneth Chang writes in the New York Times:
When the object hit Earth, carving a crater about 100 miles wide and nearly 20 miles deep, molten rock splashed into the air and cooled into spherules of glass, one of the distinct calling cards of meteor impacts[…]
Usually the outsides of impact spherules have been mineralogically transformed by millions of years of chemical reactions with water. But at Tanis, some of them landed in tree resin, which provided a protective enclosure of amber, keeping them almost as pristine as the day they formed[…]
Finding amber-encased spherules, [paleontologist Robert DePalma] said, was the equivalent of sending someone back in time to the day of the impact, "collecting a sample, bottling it up and preserving it for scientists right now."