Attica Chert
© 2003 by the Center For Social Research, Parkland College
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TEXTURE:
The texture is typically coarse, but finer grained material does sometimes occur.
LUSTER:
Luster tends to be dull.
COLOR:
Against a gray to blue-gray background will be streaks and swirls of light to medium green. In fact, another name for the material is "Indiana greenstone." Under 25X magnification the streaks and swirls resolve into masses of bright green, very small, spherical structures joined by smears of the green mineral, all of which is embedded in relatively transparent matrix. The green mineral is glauconite (Brad Koldehoff 2003: personal communication). This is a wholly distinctive attribute.
FOSSILS:
Sponge spicules will be present (Koldehoff 1999: 8-9). They are typically white although they are occasionally dark.
STRUCTURAL CHARACTERISTICS:
There are many small voids lined or filled with iron oxide. Less common are crystalline structures expressed in a moss-like pattern. The crystals are dark and may be iron pyrite. Lastly, one occasionally encounters both druse and oolites.
HEAT TREATMENT:
Attica Chert is not typically heat treated.
SOURCE:
The illustrated specimen was provided by Dr. Richard Edging, then an employee of the Illinois Archaeological Survey. It was recovered from a quarry site north of Attica, Warren County, Indiana.
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