Labradorite, a rock that consists of aluminum, calcium, and sodium silicates. It is a variety of feldspar, found in dark gray crystalline masses that are easily split into slabs. Some varieties of labradorite are beautiful when polished, showing rich shades of blue, green, and bronze. Labradorite is used for table tops and for small ornamental objects. It is found in parts of Europe and the United States, but the finest grade occurs in Labrador.
Many scientists believe that the impact from a massive asteroid was what killed off the dinosaurs. It's what started the Age of Mammals. But what if the asteroid had missed?
Every time a new fossil is found, one of the first things scientists determine is how old that fossil really is. But how do they determine it, and how can they be completely accurate?