This oblong pebble shows the initial step in manufacturing a projectile point, which has been outlined for clarity.

Native American tool makers would select small, oblong quartz pebbles from stream beds or gravel banks with which to produce projectile points.

The original smooth overall surface of these pebbles is call the "rind." The rind is produced by glacial and water action over a very long period of time.

The initial step in manufacturing a projectile point is to remove material from one side of the long axis of the oblong pebble. Once this material is removed, the specimen is termed a "turtle-back" because of it resemblance to the back of a turtle when turned over and the original, remaining rind is viewed.

The next step is to remove material from the long axis of the opposite side of the pebble, thus eliminating the original rind. The whole pebble is further thinned and reduced until its desired form is achieved.

In this case, impurities in the pebble material meant this could not be completed. So the pebble was discarded.