Desert Messenger

January 6, 2016 www.DesertMessenger.com 15 Obsidian is a shiny, glass-like stone that comes from deep within the earth and finds its way to the surface through volcanoes. It is found throughout the world in ar- eas of fairly recent volcanic activity. The glassy rock is rapidly destroyed through weathering processes, so it is rare to find obsidian older than a few million years. Significant de- posits of obsidian can be found in North, Central, and South America as well as the Mediterranean, New Zealand, South East Asia, parts of Africa, and even Iceland. In the United States it is found only in the western part of the country. Obsidian has been used by humans since the Stone Age, and is still in use today. Obsidian is used in the manufacture of tools such as blades, knives, points, and even scalpels. Once it was discovered how easily obsidian could be fash- ioned into these tools, it quickly became the raw material of choice for producing any sharp object and became one of the first targets of organized "mining." It has also been found in pottery, fashioned into plates and bowls, and even polished into mirrors. Pre-Co- lumbian Americans carved it into intricate decorative or ceremonial objects and ornaments. Ancient Meso-American peoples also made a type of double-edged sword called a macuahuitl out of a long obsidian blade mounted on a hilt made of wood. This deadly weapon com- bined the sharp cutting edge of an obsidian blade with the ragged cut of a serrated edge and was capable of inflicting terrible injuries. By Jenn Jedidiah Free for RocksInMyHead™ Tears, Needles, and a Double-edged Sword Crafting of obsidian tools may have been the world's first manufacturing industry. At some archeological sites, tons of obsidian flakes reveal the presence of ancient "factories." Some of these sites have enough waste debris to suggest that many people labored there for decades producing a variety of obsidian objects. Obsidian was so highly valued that ancient people trans- ported and traded obsidian and obsidian objects over thousands of miles. One interesting characteris- tic of obsidian is that every outcrop and flow is unique and distinctive in molecular composition and can be specifically identified. In other words, each sample of obsidian can be traced to a specific volcanic eruption. Because of this fact, it is possible through the use of electron microscopes, to identify the char- acteristics of obsidian artifacts and match them to the source outcrops. Archeologists have been able to use this technology to map trade routes of obsidian throughout North America. Geologically speaking, obsidian is an extrusive igneous form of Sili- con Dioxide (SiO2), or the mineral quartz. An igneous rock is one that is formed from the solidification of molten material. Extrusive means it erupted onto the surface where it cooled and solidified. Some other examples of extrusive igneous rocks are basalt, pumice, rhyolite, scoria, and tuff. But what distinguishes obsidian from its siblings is that it cools so rapidly that its atoms are unable to arrange themselves into a crystalline structure. Minerals are "crystalline" which means they have an ordered atomic structure ADVENTURES WITH ROCKS ™ SEE ROCKS ON PAGE 33 Desert Gardens Show Grounds EVERY SATURDAY - 1:00 PM January - February AUCTION AUCTION QUALITY ROCK RELATED CONSIGNMENTS • NO RESERVE • NO MINIMUM For more information contact: Auctioneer: Tom Brown 307-247-4119 or ttbb64@hotmail.com Show Host: Dave Walker 623-980-5746 CASH, CHECK OR CREDIT CARDS ACCEPTED

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