robably one of the most unusual gemstones is coprolite. Who, in his right mind would say that animal dung could actually become a gemstone? And yet, that is exactly what coprolite is--the agatized nodules of dinosaur excrement.
Utah is a great location to find these nodules. Those found here are usually about 2 to 4 inches in diameter and about 8 inches long. On the outside they are rather nondescript brown rocks, but check the cross section and you find red, yellow and even blue agate. It's interesting that although dinosaurs roamed in many areas, you do not always find evidence dung or bones in the same area. Some of the best preserved examples are on display at Dinosaur National Monument. These came from the Morrison formation.
archaeopteryx
a bird dinosaur
The Morrison formation was laid down about 140 million years ago during the last of the Jurassic period of the Mesozoic era. The Permian which preceded the Mesozoic, had been a period of hard times for animals. The climate was severe. Glaciers covered a large portion of the world; oceans receded and swamps and lakes dried up. Hardy conifers replaced the soft pithy water loving trees.
The Mesozoic brought less hazardous weather; glaciers melted and the land warmed. This tropical and subtropical climate was pleasing to all life. Ferns, rushes, reeds and cypress-like trees appeared. Reptiles liked these conditions, as did the first mammals. And the dinosaurs persevered for a long time. Their droppings have lasted even longer.