Florida Geological Survey - Geology Topics
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Identification: Chert, also known in Florida
as flint or flint rock, is an extremely fine-grained variety
of the mineral quartz. It is characterized by its extreme
hardness (7.0), glass-like fracture, and the sharpness of
the edges of broken fragments, Florida's cherts are
generally gray in color, though some are bright shades of
blue, red, yellow and orange.
Occurrence: Chert is found in Florida in
association with some of the limestone formations,
especially the Ocala. The material was formed by the
replacement of calcium carbonate with silica carried in
circulation ground water, as shown by the fact that much of
the chert still contains traces of the fossils that were
present in the original limestone. Chert is found at the
surface of the ground in many of the northern and western
counties of the State, especially Wakulla, Marion, and
Citrus counties.
Production and Use: Chert was utilized by
Florida's Indians in the manufacturing of axe heads, spear
heads and arrow points. The hardness and variety of
colors make chert suitable as a semi-precious stone.
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2012 State of Florida