Difference between revisions of "Raw materials"

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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.<br>
 
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.<br>
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 +
''Most lithic raw material is procured as nodules (nodules have rounded edges but can be in various shapes as opposed to a cobble which is rounded and roughly spherical). Flint is most often found in this form but there is also tabular flint that is procured from vertical or horizontal seams. Other lithic raw materials may be procured from eroded out material. Raw material such as slate will come in parallel-sided slabs.''
  
 
&nbsp;  
 
&nbsp;  
  
== Geological Background ==
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== Acquisition of raw materials  ==
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''See chaine operatoire section.''
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 +
Shorter version:
 +
 
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A raw material is selected in accordance with the purpose of production. The choice is further limited by both natural and social factors. The natural limitations should be accounted for before social factors can be discussed (Inizan et al. 1999<ref name="Inizan 1999">Inizan, M.-L., M. Reduron-Ballinger, H. Roche and J. Tixier 1999 Technology and Terminology of Knapped Stone. English ed. Translated by J. Féblot-Augustins. CREP, Nanterre.</ref>).
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===== Different purposes of production =====
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#Production of functional tools for everyday tasks: Axes, knives, scrapers, projectiles, burins, borers etc
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#Production of prestige tools (often requires raw materials of high quality)
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#Testing of raw materials
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#Apprenticeship (see technological skill)
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&nbsp;
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===== Natural limitations  =====
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If a high quality raw material is not available, the knapper must use what is available in the area. This can affect the choice and quality of tool production.
 +
 
 +
#Availability/territory
 +
#Raw material properties
 +
 
 +
=====
 +
 
 +
=====
 +
 
 +
===== Social limitations =====
 +
 
 +
The choice of raw material might be limited by background, tradition and skill.
 +
 
 +
#Tradition and personal preference
 +
#Technological skill: Beginners may have problems with selecting raw material with decent properties due to lack of experience. Usually, beginners are not using high quality material when practicing their skill.
 +
 
 +
<br>
 +
 
 +
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.<br>
 +
 
 +
== Raw material properties  ==
 +
 
 +
Several properties are considered vital to the selection of raw material for tool production. A single raw material will not necessarily inhabit all of these properties at the same time. Below a short description of these properties, which probably were considered important by prehistoric people, are listed (<u>Andrefsky 1998</u>; Crabtree 1982<ref name="Crabtree 1982">Crabtree, Don E. 1982 An Introduction to Flintworking. Occasional Papers of the Idaho Museum of Natural History 28.</ref>; Inizan et al. 1999<ref name="Inizan 1999">Inizan, M.-L., M. Reduron-Ballinger, H. Roche and J. Tixier 1999 Technology and Terminology of Knapped Stone. English ed. Translated by J. Féblot-Augustins. CREP, Nanterre.</ref>; Whittaker 1994<ref name="Whittaker 1994">Whittaker, J.C. 1994 Flint knapping: making and understanding stone tools. University of Texas Press, Austin.</ref>; <u>Eriksen 2000; Eigeland 2007</u>).
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===== Conchoidal fracture  =====
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The word “conchoidal” derives from greek and means shell or shell-like. A raw material with a conchoidal fracture will produce flakes that have the shape of a shell (or surface like a shell)
 +
 
 +
<br>The advantage of raw materials with this type of fracture is the controlled production of tools it will result in. Since a conchoidal fracture leaves a smooth surface, the knapper can shape the block or core exactly as he desires. Furthermore, it is possible to predict the next step in the production sequence since the knapper knows how the raw material will react to percussion. A rock like granite, for example, does not have a conchoidal fracture and will react differently. The granite will fracture into irregular fragments and leave a rugged surface.<br>
 +
 
 +
===== Homogeneous structure  =====
 +
 
 +
A homogenous raw material does not hold inclusions, cracks, fracture lines or other impurities. Such inclusions and cracks, like fossils and frost cracks (in which water has penetrated the pores of the rock and frozen), can make the production more difficult and less controllable due to the occurrence of unexpected fractures. Many rocks with a coarse grained texture, that is with visible minerals, will be described as heterogenous.
 +
 
 +
===== Grain size  =====
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 +
Raw materials with a fine grained texture either have minerals with no crystals (amorphic) or microscopic minerals which can not be seen with the naked eye (cryptocrystalline). A fine-grained texture is often a sign of the rock having a conchoidal fracture (but there are exceptions). Flint, for example, is a raw material with a fine-grained texture, while gneiss and granite are not. In the literature, rocks with a fine-grained texture are generally considered superior to coarse-grained rocks because they are easier to work.
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 +
===== Elasticity  =====
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The fourth property which is considered important is elasticity. A rubberball is elastic. If you squeeze it and then let go it will return to its original form. This is elasticity. The same principal is applicable to some raw materials which return to their original form after percussion (Rocks will, however, never be as elastic as a rubberball because they are brittle too, see below). A rock that lacks elasticity will often fracture during production because it can not endure the blow. A production with a raw material which lacks elasticity will often be uncontrollable due to the occurrence of unexpected fractures.
 +
 
 +
===== Brittleness  =====
 +
 
 +
Brittleness is a property that makes a raw material easy to work, that is, the knapper does not need to use much force to detach a flake. A brittle raw material immediatly responds to a blow. The advantage of brittleness is that the raw material preserves its interior quality. Repeated blows, which occur if the rock is not brittle, produce cracks and fracture lines inside the raw material which may cause mistakes at a later stage in the production. If the flakes can be detached right away, this problem is avoided.<br><br>'''Sharpness'''
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 +
Another important property of raw materials is to produce very sharp edges for cutting and projectiles. There exist several raw materials which have neither a conchoidal fracture nor a homogenous fracture, for example variants of quartz, which still produces extremely sharp edges. In many cases sharp edges might have weighted more than knapping quality.<br>
 +
 
 +
'''Durability'''
 +
 
 +
Tools produced from robust and tough raw materials will last longer and do not need to be constantly renewed. The knapper often avoids making retouch on the edges since the tool is tough due to the strength of the material. Flint, which is a brittle material, will not last as long as robust, tough materials like coarse-grained quartzites, diabase and basalt during some activities like chopping, digging and scraping.<br>
 +
 
 +
===== Availability  =====
 +
 
 +
Availability is not a geological property, but is still an important factor in the choice of raw material for tool production. To which extent raw material of good quality was available locally or had to be imported from the outside, were important factors to the prehistoric knapper. Availablity is rarly discussed in research carried out in flintrich regions.<br>&nbsp;<br>'''Colour'''
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The colour and appearance of a raw material might have been a factor in the selection of raw materials. If several different raw materials with the same technological properties were available in an area it is possible that the choice was an aesthetic one.
 +
 
 +
== Raw material types ==
  
 
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 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).  
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[[:Silicate raw materials|Silicate]] raw materials  
 
[[:Silicate raw materials|Silicate]] raw materials  
  
[[Sedimentary|Sedimentary]]&nbsp;raw materials  
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[[:Igneous raw materials|Igneous]] raw materials
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[[:Sedimentary raw materials|Sedimentary]]&nbsp;raw materials  
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[[Metamorphic raw materials|Metamorphic]] raw materials
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[[:modern raw materials|Modern]] raw materials
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[[Other raw materials|Other]] raw materials
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== Natural alteration  ==
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Main article:&nbsp;[[:natural alteration|Natural alteration]].
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Raw material, and the products of a given raw material, can be altered by both natural and human processes before, during and after production. These alterations can change the quality and appearance of a raw material which make it more difficult to interpret. Below a number of terms and processes are described to make it easier to explain what we observe.<br>''Lithic material can altered by natural processes so that they sometimes resemble tools. Such lithics are known as eoliths. Also some lithic material can appear to be polished by agencies such as wind and sand, often referred to as desert polish. Also debitage can be altered by natural processes such as heat, frost<br>and patination.''<br>
  
[[Metamorphic|Metamorphic]] raw materials
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<references />

Latest revision as of 09:23, 3 March 2010

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.

Most lithic raw material is procured as nodules (nodules have rounded edges but can be in various shapes as opposed to a cobble which is rounded and roughly spherical). Flint is most often found in this form but there is also tabular flint that is procured from vertical or horizontal seams. Other lithic raw materials may be procured from eroded out material. Raw material such as slate will come in parallel-sided slabs.

 

Acquisition of raw materials

See chaine operatoire section.

Shorter version:

A raw material is selected in accordance with the purpose of production. The choice is further limited by both natural and social factors. The natural limitations should be accounted for before social factors can be discussed (Inizan et al. 1999[1]).

Different purposes of production
  1. Production of functional tools for everyday tasks: Axes, knives, scrapers, projectiles, burins, borers etc
  2. Production of prestige tools (often requires raw materials of high quality)
  3. Testing of raw materials
  4. Apprenticeship (see technological skill)

 

Natural limitations

If a high quality raw material is not available, the knapper must use what is available in the area. This can affect the choice and quality of tool production.

  1. Availability/territory
  2. Raw material properties

=

=====
Social limitations

The choice of raw material might be limited by background, tradition and skill.

  1. Tradition and personal preference
  2. Technological skill: Beginners may have problems with selecting raw material with decent properties due to lack of experience. Usually, beginners are not using high quality material when practicing their skill.


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.

Raw material properties

Several properties are considered vital to the selection of raw material for tool production. A single raw material will not necessarily inhabit all of these properties at the same time. Below a short description of these properties, which probably were considered important by prehistoric people, are listed (Andrefsky 1998; Crabtree 1982[2]; Inizan et al. 1999[1]; Whittaker 1994[3]; Eriksen 2000; Eigeland 2007).

Conchoidal fracture

The word “conchoidal” derives from greek and means shell or shell-like. A raw material with a conchoidal fracture will produce flakes that have the shape of a shell (or surface like a shell)


The advantage of raw materials with this type of fracture is the controlled production of tools it will result in. Since a conchoidal fracture leaves a smooth surface, the knapper can shape the block or core exactly as he desires. Furthermore, it is possible to predict the next step in the production sequence since the knapper knows how the raw material will react to percussion. A rock like granite, for example, does not have a conchoidal fracture and will react differently. The granite will fracture into irregular fragments and leave a rugged surface.

Homogeneous structure

A homogenous raw material does not hold inclusions, cracks, fracture lines or other impurities. Such inclusions and cracks, like fossils and frost cracks (in which water has penetrated the pores of the rock and frozen), can make the production more difficult and less controllable due to the occurrence of unexpected fractures. Many rocks with a coarse grained texture, that is with visible minerals, will be described as heterogenous.

Grain size

Raw materials with a fine grained texture either have minerals with no crystals (amorphic) or microscopic minerals which can not be seen with the naked eye (cryptocrystalline). A fine-grained texture is often a sign of the rock having a conchoidal fracture (but there are exceptions). Flint, for example, is a raw material with a fine-grained texture, while gneiss and granite are not. In the literature, rocks with a fine-grained texture are generally considered superior to coarse-grained rocks because they are easier to work.

Elasticity

The fourth property which is considered important is elasticity. A rubberball is elastic. If you squeeze it and then let go it will return to its original form. This is elasticity. The same principal is applicable to some raw materials which return to their original form after percussion (Rocks will, however, never be as elastic as a rubberball because they are brittle too, see below). A rock that lacks elasticity will often fracture during production because it can not endure the blow. A production with a raw material which lacks elasticity will often be uncontrollable due to the occurrence of unexpected fractures.

Brittleness

Brittleness is a property that makes a raw material easy to work, that is, the knapper does not need to use much force to detach a flake. A brittle raw material immediatly responds to a blow. The advantage of brittleness is that the raw material preserves its interior quality. Repeated blows, which occur if the rock is not brittle, produce cracks and fracture lines inside the raw material which may cause mistakes at a later stage in the production. If the flakes can be detached right away, this problem is avoided.

Sharpness

Another important property of raw materials is to produce very sharp edges for cutting and projectiles. There exist several raw materials which have neither a conchoidal fracture nor a homogenous fracture, for example variants of quartz, which still produces extremely sharp edges. In many cases sharp edges might have weighted more than knapping quality.

Durability

Tools produced from robust and tough raw materials will last longer and do not need to be constantly renewed. The knapper often avoids making retouch on the edges since the tool is tough due to the strength of the material. Flint, which is a brittle material, will not last as long as robust, tough materials like coarse-grained quartzites, diabase and basalt during some activities like chopping, digging and scraping.

Availability

Availability is not a geological property, but is still an important factor in the choice of raw material for tool production. To which extent raw material of good quality was available locally or had to be imported from the outside, were important factors to the prehistoric knapper. Availablity is rarly discussed in research carried out in flintrich regions.
 
Colour

The colour and appearance of a raw material might have been a factor in the selection of raw materials. If several different raw materials with the same technological properties were available in an area it is possible that the choice was an aesthetic one.

Raw material types

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

Igneous raw materials

Sedimentary raw materials

Metamorphic raw materials

Modern raw materials

Other raw materials

Natural alteration

Main article: Natural alteration.

Raw material, and the products of a given raw material, can be altered by both natural and human processes before, during and after production. These alterations can change the quality and appearance of a raw material which make it more difficult to interpret. Below a number of terms and processes are described to make it easier to explain what we observe.
Lithic material can altered by natural processes so that they sometimes resemble tools. Such lithics are known as eoliths. Also some lithic material can appear to be polished by agencies such as wind and sand, often referred to as desert polish. Also debitage can be altered by natural processes such as heat, frost
and patination.

  1. 1.0 1.1 Inizan, M.-L., M. Reduron-Ballinger, H. Roche and J. Tixier 1999 Technology and Terminology of Knapped Stone. English ed. Translated by J. Féblot-Augustins. CREP, Nanterre.
  2. Crabtree, Don E. 1982 An Introduction to Flintworking. Occasional Papers of the Idaho Museum of Natural History 28.
  3. Whittaker, J.C. 1994 Flint knapping: making and understanding stone tools. University of Texas Press, Austin.