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Larry will add to pictures on this page every now and then. He also plans to offer other pages with different chert types. His goal is to present a variety of chert types, and their variations, found in his area of Illinois
Below, are some pics of the beautiful chert from Missouri called Crescent Quarry Burlington. As you can see, it's very colorful and may have been confused with Flint Ridge in the St. Louis area. Many of the old collectors thought it had to be Flint Ridge if it had that much color.
(click on the pictures to enlarge)
(photo LK) (raw)
The cortex is generally white to off white and there are usually lots of fossils in the cortex with some fossils in the chert. Both healed and unhealed fractures are also common as can be seen in the close-ups. This colorful chert appears to be extremely isolated in the Crescent Quarry area. Many micro-drills, from Cahokia Mounds, were made from this material. The vast majority of the micro-drills are raw chert.
(Photo LK) (raw)
If you compare the photos above (raw Crescent) with those below (heated Crescent), you can see that heat-treating doesn't change the color that much. However, the glossiness and workability are greatly enhanced by heat-treating
(Photos LK) (heated)
(Photo LK) (Photo LK)
Here's some fossils found in Crescent Quarry, Burlington, Chert. They are found in the regular Crescent Quarry and Colorful Crescent Quarry Cherts. The example on the right show a cacoon-like fossil in the Colorful Crescent. It also shows the cortex (bottom) and the deep rust-colored fracture stains (to the lower left of the fossil). In Colorful Crescent, the fractures run from rust-colored, to bright red, to jet black, often in the same nodule.
For more information, check out the Parkland College CHERT TYPES pages.