What are points made from?

One rarely finds a naturally pointed stone of the right size, shape, and weight for use as a projectile point. A suitable projectile point must be made. To do so, one must first find a proper stone and shape it. In Illinois, Native Americans generally selected chert, a silica-rich stone, to make projectile points and other types of stone tools.

Chert is commonly found in limestone and dolomite deposits exposed along some rivers and streams. Particularly rich outcrops of chert-bearing rock are found in the rugged Shawnee Hills of southern Illinois and the towering limestone bluffs that border the lower reach of the Illinois River Valley.

In these areas, and others across the state, chert may be quarried from bedrock or streambeds, where it accumulates as the stream cuts through bedrock. Native Americans searched these places to find pieces of chert of the right size, shape, and quality.

What is the difference between chert and flint?
In Illinois, and elsewhere in the Midwest, archaeologists generally identify the stone used to make a projectile point as chert or flint. The basic composition of chert and flint are identical: both are hard, dense microcrystalline or cryptocrystalline sedimentary rock. They have a conchoidal (shell-shaped) fracture pattern. They occur principally as nodules and less commonly as layered deposits.

There is considerable confusion about the other characteristics of chert and flint. According to one source (Bates and Jackson 1984:85), chert may be white or variously colored, although they later note that flint is a dark gray or black variety of chert (Bates and Jackson 1984:187). Pough (1960) notes that flint is a compact variety of chert, and black in color. However, Leet and Judson (1965) state that flint is commonly found in certain limestone beds such as the chalk beds of southern England, and that chert is similar to flint but tends to be lighter in color. Finally, Pohopien (1969) reports that the color of chert is white, yellowish, brown, gray, and black, and when chert is found in chalk beds, it is called flint.

The majority of projectile points found in central Illinois were made from white to light gray, silica-rich rock, which we generally refer to as chert.