Cairngorm, (also called Scottish topaz or smoky quartz), a smoky, yellow-brown variety of quartz. It is named for the Cairngorm Mountains of Scotland. The stone is highly prized in Scotland and is used for various ornamental purposes. Its value depends on transparency and shading. The mineral has been found in Great Britain, Siberia, Spain, and Switzerland, and near Pikes Peak, Colorado.
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?
La Brea Tar Pits, an area in Hancock Park, Los Angeles, where there is a natural accumulation of sticky asphalt derived from an ancient petroleum seep.