Stone Tool Characteristics
Stone tools in a broad sense result from striking pieces, flakes or blades from a block of material, the core. All flakes of human origin have distinctive characteristics and hallmarks that distinguish them from natural/unintential flakes.
Flakes of human origin have an exterior surface, representing the exterior of the core, and an interior surface created by the fracture. The interior surface of a flake resulting from an intentional fracture, caused by striking the core material with a hammer, either a stone or a piece of antler or wood, exhibits characterisic halmarks.
The application of the striking force initiates a curved shell-like (conchoidal) fracture in many fine-grained materials such as flint resulting from the concentric waves of presure propagating through the stone in the shape of a cone. Just below the point of percussion, the pressure cone produces a bulb on the interior surface of the flake. Depending on the hammer used, the bulb of percussion is often accompanied by a scar and small fissures running in a radial direction from the point of percussion. Often concentric ripples can be seen radiating distally from the point of percussion. These ripples are most pronounced on fine grained materials such as obsidian (vulcanic glass) and flint but are almost invisible on course-grained materials such as quartzite.
The exterior surface (see below) can be quite variable depending on the original core from which the flake was struck. The flake shown here (L=4.5cm; W=4.5cm; T=0.5cm) displays a large negative flake scar which is the remnant of a previously removed flake. After removal, the final flake was worked along the edges and delicately retouched along the distal edge for use as a scraper for hide working. The early Neolithic scraper, shown here as an example, dates from 6,000 years ago and was found in Somerset, England.
The core nodules from which flakes were produced can also be recognised by the scars and ridges from removed flakes and negative impressions of the percussion bulb close the striking platform of the core. This is a neolithic core (L=9cm; W=7cm; H=8.5cm) from a famous Neolithic flint mine site in the south of the Netherlands.
Here is a link to an excellent guide to help distinguish intentional flaking products from those produced by natural processess: flint id guide.pdf.
