The dinosaurs were one of Earthís most successful creatures. Their reign lasted approximately 120 million years in the period known as the Mesozoic Era (The Age of Reptiles). They are thought to have first appeared in the late Triassic, about 200 million years ago, and evolved and diversified thru the Jurassic Period (180-135 million years ago). By the end of the Cretaceous About 70 million years ago) they were extinct.
What we today call dinosaur bone is more correctly and descriptively known as silicified fossil of dinosaur bone. Fossils are the remains of prehistoric animals or plants. Silicified means the fossil is quartz (a form of silica). A more common name for this form of quartz is agate.
Usually fossils are some hard skeletal part on an organism, slow to decay, that has been quickly buried in sediment, preserving them more or less intact until petrification begins. Bones, teeth, shells and wood are often preserved in this manner.
Petrification is a complex process in which groundwater is an essential ingredient as it carries the mineral solutions that permeate and replace the buried remains of a living organism. In some cases these mineral bearing solutions fill the cavity left by the decay of the buried object; in other cases they replace the porous areas in the buried organic material with another mineral taken from the surrounding sediments, silica in the case of gem quality dinosaur bone.
In the most optimal of cases, the most delicate and minute details of the cellular structure of the original bone have been reproduced. Molecules of the organic material are removed and replaced bit by bit by inorganic material (silica in solution). The fact that living bone is nourished thru a highway of blood vessels makes the petrification process more possible as these same highways now conduct the mineralized water. The colors in agatized fossils come from trace minerals, metallic salts, in the silica solution. The vivid and unexpected colors and patterns can be magical and delightful.
Although fossilized dinosaur bones are found in many places around the world, from Argentina to Mongolia to Madagascar, the highly silicified and beautifully colored dinosaur bone that weíre most interested in, sometimes called gem bone, is almost exclusively found in a relatively small area in the United States, the Colorado Plateau. Now days, it is a semi desert region centered a bit north of the Four Corners, where the states of Arizona, New Mexico, Utah, and Colorado touch. Most of the areas that produce quality bone are in Colorado and Utah. When the dinosaurs lived there it was an area that included both land and water, with swamps, lakes, and shallow oceans bordered by continental shelf, rising into ancient mountains. As geologic time passed the climate changed, becoming more arid. Volcanic activity increased, and with it volcanic sediments, rich in silica were carried by the rivers and deposited as the seas retreated. This proved to be an ideal environment for the burial and subsequent preservation of the remains of many a dinosaur.
Today, itís quite difficult to go out and collect dinosaur bone. In fact, itís illegal to do so on government land unless you are a research scientist with permission from the Bureau of Land Management, which manages the pubic domain. Although private lands occasionally yield a bit of new material, most gem bone was collected long ago. Prospectors searching for uranium discovered lots of it in the 1950ís, as bone is sometimes found within sediments containing uranium ore.
Beautiful bone cut and polished to display interesting patterns, especially when it shows high contrast and vivid colors is quite popular with collectors. As is the case with many materials in limited supply, it is especially appreciated and sought after by local collectors, who are more fully aware of itís rarity in finer grades and are knowledgeable of its value. The variety of color and pattern is amazing. Some pieces are transparent when cut thin, with the bone marrow cell membrane forming a spider web pattern. Some bones are hollow, with a core of amethyst crystals. The patterns revealed through cutting and polishing vary with the type of bone, the direction of the cutting through the bone, whether across it, or along it, or diagonal across it. Each produces a different look. Between variations in pattern and variations in color, the choices are almost limitless. There is a stone for almost any taste, from those who prefer the subtle and understated to those who want their stones to be bold and unusual. Dinosaur bone is a stone with a certain magical allure, enduring and preserving a bit of our past, from the absolute mists of time, a stone that anyone with a sense of the fleeting nature of time should find attractive and magical.