In lithic analysis

Lithic analysis

In archaeology, lithic analysis is the analysis of stone tools and other chipped stone artifacts using basic scientific techniques. At its most basic level, lithic analyses involve an analysis of the artifact’s morphology, the measurement of various physical attributes, and examining other visible...

 (a subdivision of archaeology

Archaeology

Archaeology, or archeology , is the study of human society, primarily through the recovery and analysis of the material culture and environmental data that they have left behind, which includes artifacts, architecture, biofacts and cultural landscapes...

), an eraillure is a small secondary flake removed from a lithic flake

Lithic flake

In archaeology, a lithic flake is a "portion of rock removed from an objective piece by percussion or pressure," and may also be referred to as a chip or spall, or collectively as debitage. The objective piece, or the rock being reduced by the removal of flakes, is known as a core. Once the proper...

's bulb of force

Bulb of applied force

In lithic analysis, a subdivision of archaeology, a bulb of applied force is a defining characteristic of a lithic flake...

, which is a lump left on the ventral surface of a flake after it is detached from a core of tool stone

Tool stone

The term tool stone has multiple meanings.In archaeology, a tool stone is a type of stone that is used to manufacture stone tools.Alternatively, the term can be used to refer to stones used as the raw material for tools....

 during the process of lithic reduction

Lithic reduction

Lithic reduction involves the use of a hard hammer precursor, such as a hammerstone, a soft hammer fabricator , or a wood or antler punch to detach lithic flakes from a lump of tool stone called a lithic core . As flakes are detached in sequence, the original mass of stone is reduced; hence the...

. The mechanics of eraillure formation are related to the propagation of a Hertzian cone

Hertzian cone

A Hertzian cone is the cone of force that propagates through a brittle, amorphous or cryptocrystalline solid material from a point of impact, eventually removing a full or partial cone. An example often occurs when a plate-glass window is struck by a small object, such as an airgun projectile...

 of force through the cryptocrystalline matrix of the stone, but the particulars are poorly understood. Eraillures usually form only when a hammerstone

Hammerstone

In archaeology, a hammerstone is a hard cobble used to strike off lithic flakes from a lump of tool stone during the process of lithic reduction. The hammerstone is a rather universal stone tool which appeared early in most regions of the world including Europe, India and North America...

 is used for lithic reduction, and then only occasionally; use of 'soft' hammer fabricators made from bone

Bone

Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...

, antler

Antler

Antlers are the usually large, branching bony appendages on the heads of most deer species.-Etymology:Antler originally meant the lowest tine, the "brow tine"...

, and wood

Wood

Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...

produce different flake characteristics but may also produce an eraillure in rare cases.