Chert

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.