BACK TO: FLINT TYPES
Crescent Quarry, Burlington, chert is found in abundance at archaeological sites throughout Illinois and some surrounding states. In it's raw state, it provides a strong tool that holds an edge well. In it's heat-treated state, It makes a sharper edge and is easily knappable. Generally, in the Cahokia Mounds area, almost 80% of the chert used is raw Crescent Quarry.
Above, is some of the finest raw Crescent. It's almost icy-blue when uncovered and patinas to a bright white.
Some ancient quarry pits at the Route 66 park. (Pictures taken in July, 1981, by LK)
Bustin' up a large nodule with a short-handled, 12-lb. sledge.
Bustin' a 400 pounder.
Check out Dr. Michael Fuller's site on Crescent Quarries.
These Burlington fossils are present in both the regular and colorful Crescent Quarry cherts.
The wood grain, raw, Crescent above occurs in both the Colorful and regular Crescent Quarry Burlington. This is a grainy piece. It gets much finer than shown here. (PhotosLK)
Above, is a typical piece of Regular, raw, Crescent. It shows the high quality chert, cortex, and rust colored cleaves in the fracture lines.
Burlington chert also occurs in many creeks in both Missouri and Illinois. Here's some from Missouri. A Missouri creek while chert is being collected.
Much of the Burlington chert has a "pock-marked" appearance. That's because, during floods, nodules, spalls, and flakes travel downstream with quite a bit of speed and hit other rocks. Those collisions, produce the small cone fractures seen here.
High quality Burlington.Make sure to test every piece, at both ends. You'll notice that the exterior, water-worm, patinated, surface, looks much different than the interior.
Remember to check both ends of the piece because you can have excellent rock in one end and junk at the other.
You'll want to reject poor specimens, like this. Notice the "grainey" or granular structure, rather than the "waxy", or "greasy" feel of the good stuff. Heat-treating would help this sample, but it still won't be as good as the "good" stuff.
For more information, check out the Parkland College CHERT TYPES pages.