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Outcrops on the slopes of Iron Mountain in Union county, Illinois, a ridge that runs north and south found approximately 4 miles west of Cobden, IL and on a tributary of Big Creek in Union County.
Ranges from white to yellow to tan, from brown to orange to red. Heat treating can bring out orange, yellows and reds and even a lilac purple.
High quality, waxy to porcelaneous in luste and very vitreous after heat treatment. Translucent. A web like pattern of banding occurs because of light refracting off of fractured edges or because of a more porous area being stained. The texture of Kaolin chert is coarse-to fine-grained. Kaolin’s cortex has a pitted texture with a yellow, white, or black color.
University of Iowa
Ranges from white to yellow to tan, from brown to orange to red. Heat treating can bring out orange, yellows and reds and even a lilac purple.
High quality, waxy to porcelaneous in luste and very vitreous after heat treatment. Translucent. A web like pattern of banding occurs because of light refracting off of fractured edges or because of a more porous area being stained. The texture of Kaolin chert is coarse-to fine-grained. Kaolin’s cortex has a pitted texture with a yellow, white, or black color.
University of Iowa