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 simply a flake, 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 tool stone has been selected, a percussor or pressure flaker (e.g., an antler tine) is used to direct a sharp blow, or apply sufficient force, respectively, to the surface of the stone, often on the edge of the piece. The energy of this blow propagates through the material, often (but not always) producing a Hertzian cone of force which causes the rock to fracture in a controllable fashion. Since cores are often struck on an edge with a suitable angle (
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In archaeology, a lithic core is a distinctive artifact that results from the practice of lithic reduction. In this sense, a core is the scarred nucleus resulting from the detachment of one or more flakes from a lump of source material or tool stone, usually by using a hard hammer precursor such as a hammerstone. The core is marked with the positive scars of these flakes. The surface area of the core which received the blows necessary for detaching the flakes is referred to as the striking platform.
In archaeological terminology, a projectile point is an object that was hafted to a weapon that was capable of being thrown or projected, such as a javelin, dart, or arrow. They are thus different from weapons presumed to have been kept in the hand, such as knives, spears, axes, hammers, and maces. Stone tools, including projectile points, can survive for long periods, were often lost or discarded, and are relatively plentiful, especially at archaeological sites. They provide useful clues to the human past, including prehistoric trade.
Knapping is the shaping of flint, chert, obsidian, or other conchoidal fracturing stone through the process of lithic reduction to manufacture stone tools, strikers for flintlock firearms, or to produce flat-faced stones for building or facing walls, and flushwork decoration. The original Germanic term knopp meant to strike, shape, or work, so it could theoretically have referred equally well to making statues or dice. Modern usage is more specific, referring almost exclusively to the hand-tool pressure-flaking process pictured.
Understanding and optimizing the effects of edge states and nanoflake dimensions on the photon harvesting efficiency in ultrathin transition-metal dichalcogenide (TMD) semiconductor photoelectrodes is critical to assessing their practical viability for sol ...
Amer Chemical Soc2017
The layered semiconducting transition metal dichalcogenides (TMDs), such as MoS2, WS2, MoSe2, and WSe2, are promising light absorbers for solar energy conversion applications due to their superior optoelectronic properties and chemical stability, however s ...