Raw material refers to the stone from which debitage, tools etc. are produced. A number of raw materials were used in pre-history, the most common feature of these materials is that they have the property of conchoidal fracture thus enabling the knapper to control the core and produce predictable outcomes of the knapping procedure.
Raw materials cover the minerals and rocks that were utilized to produce tools during the Stone Age. These raw materials have certain properties which makes it possible for a toolmaker to control and predict the production of tools by using intentionally chosen methods and techniques. This overview is not complete, but gives a good impression of preferred raw materials in the norwegian Stone Age. The overview seeks to explain why these raw materials were selected for tool production.
Geology is the science of the Earth and especially the composition of the earth’s crust and its development through time. Almost every natural raw material is found in the geological construction of the crust (Bjørlykke 2000:9).
Geology in archaeology
Minerals and rocks are the most stable and resistant materials of the earth’s surface. This is why Stone Age tools produced in these materials will outlast tools of organic materials. Thus, knowledge of geology is important to explore the largest source of information of the early prehistory. During the Stone Age a number of different minerals and rocks were utilized. For the prehistoric toolmaker the procurement of applicable raw material was the first, and most important, step of the tool production.
The availability of high quality raw materials vary, and is further limited by the geological circumstances of a given area. In many cases, the localization of a site and the movement across the landscape (mobility) can be more or less determined by the raw material sources. As archaeologists, it is important to know where certain types of raw materials can be found and which properties they inhabit. As such it is important to know how minerals and rocks are defined and separated into distinct groups after their geological origin.
Raw material types
A rock consists of two or more minerals (Dons 1996:7). Rocks are divided into three main categories based on origin. These categories are described in their separate pages
A mineral is a chemical element or a chemical compound formed by geological processes (Dons 1996:7). There exists over 4000 minerals, but only between 20-25 of these are common enough to form rocks. A few examples of well known minerals are quartz, feldspar, orthoclase, fluorite, muscovite and olivine. Every mineral has a specific chemistry and structure which gives it distinctive physical properties like color, hardness and fracture. It is the chemical compound which is the key to understand why some minerals were exploited in prehistory. Quartz (Sio2) is the most constant of all minerals, and fine grained variants of this mineral (silicates) were often utilized to make tools.
Silicate raw materials
Sedimentary raw materials
Metamorphic raw materials