Platteville-Galena Chert
© 2003 by the Center For Social Research, Parkland College
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TEXTURE:
The texture is typically fine grained although medium grained material does sometimes occur.
LUSTER:
Luster tends to be dull to waxy.
COLOR:
Colors range widely in grays and browns but tend to lighter values. Distinctive is the conspicuous presence of mottles or swirls.
FOSSILS:
A wide range of fossils can occur including sponge spicules, brachiopods, bryozoans, and corals (Ferguson and Warren 1992: 9-10).
STRUCTURAL CHARACTERISTICS:
There are no distinguishing strucutral attributes.
HEAT TREATMENT:
The colors of Platteville-Galena Chert will become reddish or reddish-brown. Luster will be enhanced (Higby 2003).
SOURCE:
The illustrated specimens were generously provided by Jacquelin Ferguson and Robert Warren of the Illinois State Museum. They were recovered from, in descending visual order: French Canyon, Starved Rock State Park, LaSalle County, Illinois; Vermilion River, near the village of Lowell, LaSalle County, Illinois; Vermilion River, near the village of Lowell, LaSalle County, Illinois; Vermilion River, near the village of Lowell, LaSalle County, Illinois.
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