Desert Messenger

September 04, 2013

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14 September 4, 2013 ADVENTURES WITH ROCKS Buttes, Bad Lands & Banded Agates By Jenn Jedidiah Free South Dakota is known for its amazing geology ranging from Badlands buttes rising up out of the vast grasslands to massive limestone and granite formations covered with Ponderosa Pine in the Black Hills. But South Dakota is also home to an amazing, and equally exciting, variety of gemstones and minerals including several beautiful kinds of agates. In fact, the state gemstone of South Dakota is the gorgeous and rare Fairburn Agate. Agates in and of themselves are amazing. Unlike other gemstones, each agate is unique. Even slabs cut from the same stone will vary in design, color, and pattern. The most common and distinctive type of agate pattern is called a fortification, where the bands crystallize into concentric layers that follow the shape of the cavity. Some other patterns of solid agates are waterline, tube, eye, plume, and seam. Agates in South Dakota contain all sorts of colors, ranging from earth tones to bright reds, oranges, and purples. Agates develop as silica deposits in cavities or pockets caused by trapped gases in (typically) volcanic host rock. As the host rock cooled and hardened, small cracks developed that allowed the gases to escape. Later these cavities filled layer by layer with fluids that were rich in dissolved silica (chalcedony or quartz) and other minerals. The colors and arrangement of these microcrystalline bands are influenced by pressure, temperature, and mineral content that occurs during the formation of the agate. If the pressures and temperatures changed while the agate was forming, bands and patterns would also change, or another form of silica, macrocrystalline quartz (quartz crystals) would then fill in the remainder of the cavity. The most famous, and also the least common and most valuable, agate found in South Dakota is the Fairburn Agate. Fairburns are fortification agates and occur in just about every color combination imaginable. Other agates found in the Grasslands and buttes of South Dakota are Prairie Agates, Water Agates, and interesting "Bubble Gum" Agates. Prairie and Water Agates are seam agates, while Bubble Gum Agates are eye agates. The primary area for these agates to be found is a wide band just outside the Black Hills that extends from just east of Rapid City through the Buffalo Gap Grasslands along the White and Cheyenne Rivers into Nebraska. The fabulous TeePee Canyon agate is a fortification agate found on the eastern edge of the Black Hills. The Gratitude Book Project releases its new summertime memory eBook and I'm in it! Get your FREE copy here: Shanana "Rain" Golden-Bear Co-Author Fairburn, Prairie, Water, and Bubble Gum Agates all can be found in agate beds scattered throughout the Buffalo Gap National Grasslands. Here, multicolored hills and buttes of volcanic badlands rise up out of the prairie, covered with pebbles that have been left behind as the surface layers erode away. Amidst all these pebbles can be found Prairie, Water, and Bubble Gum agates, as well as the elusive Fairburns. Beautiful quartz, rose quartz, and smokey quartz pebbles can also be found here, along with an occasional fossil. Three of the most productive locations for Fairburns and their counterparts are the Agate beds at Fairburn, Railroad Buttes, and Kadoka. agates which are found on or embedded in the surface of soft tuff, TeePee Canyon agates are located several feet down within the brownish limestone and must be chiseled, chipped, dug, and otherwise broken free. The extra effort is worth it, though, for the sheer beauty of these stones. If you are heading through the western part of South Dakota, your trip would not be complete without stopping to collect some of these beautiful gemstones along the way. For photos and information on South Dakota agates and collection locations, directions to the sites, camping, and more, go to our Blog Adventures with Rocks at, TeePee Canyon Agates are fortification or you can access it through the Media agates found in the eastern edge of the Link at the top tool bar of our website Black Hills near the SD/Wyoming bor- We have der. TeePee Canyon agates are charac- a nice selection of Fairburn and Teeterized by intense patterns of purples, Pee Canyon agates, as well as Prairie, reds, and oranges encased in a choco- Water, and BubbleGum agates. We late brown limestone host rock. Tee- will be open in Quartzsite in NovemPee Canyon agate nodules are found in ber at A37 in Rice Ranch, but you can exposed seams of rock in the TeePee order over the phone (605-376-8754) Canyon area of the National Forest just and by email through the website until off of Highway 16 west of Custer. Un- then. Happy prospecting and see ya in like Fairburns and other Grasslands Quartzsite! Got Drugs? Turn in your unused or expired medication for safe disposal Mon - Fri. 8am-5pm Quartzsite Police Department

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