20 Raw material for stone tools

Dr. Krishnendu Polley

Contents:

1. Introduction
2. Quality or Property of Lithic Raw Material
3. Brief Description of Different Lithic Raw Materials
4. Lithic Raw Material Procurement Strategies Summary

Learning Outcomes:

After studying this Module you will

•  have some ideas on the basic stone types, used by the Stone Age people to make their tools;
•  learn basic qualities and fracture properties of the rocks and mineral, ideal for making stone tools; and
•  have some basic ideas on the raw material procurement strategies, used by the prehistoric people.

1. Introduction:

The appearance of stone tool technology in course of hominid evolution marks a radical behavioral shift from the rest of the animal world. Humans and human like creatures were making stone tools before the discovery of fire. In this regard it can be argued that stone or rock has been one of the most important kinds of raw material during most of the human existence. Archaeological evidences show that in the course of human history, earliest evidences of using stone tools dated back to 2-3 million years ago (mya)(Phillipson, 2005). Use of stone tools for various day to day activities continues even today (e.g. use of stone mortar and pastel, and occasionally use of stone utensils in daily activities).

The reasons behind using stone as primary raw material for tool making are that it is very hard and able to produce sharp working edges when fractured. A wide range of tasks can be executed with even a simple stone technology, including animal butchery (hide slitting, disarticulation, meat cutting, bone breaking), woodworking (chopping, scraping, sawing), hide scraping, plant cutting, and bone and antler working. Although other perishable materials, such as wood, bone, horn, and shell, were probably used early in the evolution of hominid technology, tools made of stone are relatively indestructible and so provide the longest and most detailed record of prehistoric tool manufacture. Stone tools supplemented biology as a means of adapting to the environment during the course of human evolution, and the study of their manufacture and potential uses reveals important information about the evolution of human culture.

2. Quality or Property of Lithic Raw Material:

The important rocks, used by the prehistoric people for making majority of their tools belong to mainly one mineral group, the quartz group of rocks, which have a single chemical constituent, SiO2 (Si 46.7 percent, O 53.3 percent), and a number of important physical characteristics in common. Varieties within the group have important differences in colour, lustre, fracture properties, specific gravity, external shape and size, origin, occurrence, impurities, transparency and other features. But these differences are overshadowed by a few qualities in common. Of these an important one is the extreme hardness, an average of 7 on the 10 degree scale of Mohs. Only topaz (8), corundum (9) and diamond (10) are harder. An essential quality of many varieties of quartz, which determined its choice by man  was isotropism (glassy quality), that is completely uniform physical properties in all directions, as opposed to crystalline rocks (Semenov, 1964).

In nature quartz can be found in two different varieties- one is crystalline and the other is non-crystalline variety. In crystalline variety quartz crystals are often encountered in the form of rock crystal. The quartz crystals may be large, are elongated hexagonal prisms terminating in hexagonal pyramids (hexagonal bipyramidism). It is characteristic of this that the individual crystals have isotropic structure and do not break down into new crystals or crystalline grains, as is the case with many other non-isotropic materials with completely ill-knit structure. Non-crystalline silica on the other hand is known to us as flint, chalcedony, obsidian, agate, jasper, quartzite etc. These groups of rocks also have isotropic properties and they give a distint type of fracture, due to these facts when broken all these crystalline and non-crystalline group of rocks produce extremely sharp cutting edge, which may be 210 to 1050 times sharper than surgical steel knife, 100 to 500 times sharper than a razor blade and 3 times sharper than a diamond blade (Semenov, 1964; Haviland, 1990:84).

Prehistoric people selected suitable rocks or minerals for making their stone tools only on the basis of the fracture property of rocks or minerals. From the study of the fracture property of various types of rocks and minerals, used by prehistoric people to make their tools, it is observed that, most of these rocks fracture in a reliable and predictable manner which is known to the archaeologists as conchoidal fracture. The term conchoidal fracture named after the shell or conch like ripples or swirls generally evident in the artifacts manufactured in finer-grained lithic raw materials.Conchoidal fracture is sometimes known as Hertzian Cone Fracture because in this type of fracture the fractured stone flakes are initiated or started by the formation of Hertzian cone at the point of applied force (Fig 1).

Fig 1: Schematic diagram of conchoidal fracture in a blick of stone (modified after Banning, 2002).

Beside this typical fracture property the lithic raw material must be elastic but brittle, and homogeneous both in crystalline structure (amorphus or crypto-crystalline) and in lacking cracks, inclusions and other flaws. The homogeneity of the crystalline structure is visible in the texture as a freshly flaked surface. The crystalline structure is also the most important factor in how easily a material works. The most homogeneous materials with amorphous crystalline structures, like glass and obsidian, fracture very easily, with extremely sharp edges and smooth fracture surfaces. Cryptocrystalline materials like flint and chert are harder, more difficult to fracture, and do not form such sharp edges. The fracture surfaces are smooth to slightly rough, although in most cases the crystal structure is invisible to the naked eye. The toughest and least amorphous materials like basalt or quartzite are hard to work, and the fracture surfaces are usually rough with a grainy or sugary texture (Whittaker, 2009).

3. Brief Description of Different Lithic Raw Materials:

The study of rocks in archaeology is based mainly on chemical, physical, geologic, and mineralogic investigation; this entails identifying the composition of the stone, characterizing its structure and other physical properties, and elucidating the changes that it may have undergone since it was created or last used (Jeffery and Hutchison 1981; cited in Goffer, 2007). More specific studies of stone, however, are often conducted in the framework of Petrology, the science that deals with the origin, composition, and structure of rocks; and Petrography, the classification and systematic description of rocks (Kempe and Harvey 1983, cited in Goffer, 2007). Beside the geochemical and geophysical methods of identification of lithic raw materials fracture properties of various rocks must be known by the archaeologists for understanding variation in lithic tools as well as for understanding typo-technological attributes of lithic artifacts. Here a brief description of different lithic raw materials are given below, which were preferred by prehistoric man to make their tools-

Quartz:

Quartz is the second most abundant mineral in the earth’s crust. It is hard, 7 on Moh’s scale, and resistant to many forms of chemical weathering. The chemical composition of quartz consists of 99.9% of SiO2 and some impurities of other minerals. In natural condition quartz may be found as macrocrystalline variety and microcrystalline variety. Several microcrystalline varieties of quartz are common in nature, especially as sedimentary and metamorphosed rock. Among the members of chert group, including flint, chert and jasper, are composed of an aggregate of microcrystalline quartz crystals. On the other hand members of chalcedony group, which includes chalcedony, carnelian and agate, are characterized by aggregates of sheaves of radiated microscopic water bearing silica crystals (Hefferan and O’Brien, 2010:137).

Large quartz crystals are usually watery transparent in colour with glassy luster. This variety of quartz usually fractures in flat conchoidal form and is not very suitable for making prehistoric tools. However, recent work by Hermida (2008) has shown that not all quartz crystals fracture in the above mentioned manner and sometimes formation process and Petrological nature of quartz determines its mechanical properties. It is further found that since quartz is not a homogeneous material because of the presence of internal flaws and crystalline surface, it produces non-intentional breakage. Only the upper part of large quartz crystals is homogeneous. As a result of this, quartz fracture ranges from conchoidal to uneven (Hermida, 2008:103).

Large quartz crystals were very rarely used by the prehistoric people to make their tools. In Zhoukoudien of China a very few implements made on large quartz crystals are recovered by the archaeologists (Semenov, 1964:33). However grainy quartz is found to be used in various sites of France and Spain, and it is also found that sophisticated technologies like Levalloisian technology were successfully applied on this variety of raw material (Hermida, 2008:104). In Africa also white milky quartz were used as principal raw material for various African Late Stone age industries (Cornelissen, 2003) like Nachikufan industry of Zambia (Bisson, 1990).

Use of large quartz crystals and milky white quartz are found at a number of lower Paleolithic sites of eastern India. Works of Ghosh (1966), Ghosh et al (1991) in West Bengal, Mohapatra (1962) in Orissa and Ghosh (1970) in Singhbhum region of Jharkhand have shown that lower Paleolithic people of this region used a significant amount of locally available quartz pebbles to make their tools.

Obsidian:

Obsidian is a natural glass produced by volcanic action. It is related chemically to rhyolite and granite, and therefore includes large amounts of non-silica minerals such as potassium, feldspar as well as quartz. Obsidian contains 75 percent of quartz (SiO2) into it. It has hardness 6 in Mohs scale and its specific gravity is 2.35 to 2.5. Extremely rapid cooling of the molten rock prevented the formation of distinct crystals, which is what distinguishes obsidian from its chemical relatives. Usually the color is dark, most often black, but there are also red, brown, stripped (red/brown/black), green, gray, silver and clear obsidian. Textures range from perfectly homogeneous and glassy to rather crystalline with a grainy, sugary texture. Some obsidian has crystals, bits of tuff, or other inclusions, or strange cracks and stress lines from uneven cooling. In nature obsidian occurs in large massive flows in some places and as lumps or beds in rhyolite flows.

Obsidian was prized by many prehistoric groups. Uses of obsidian for making tools have been recorded from lower Paleolithic times. In Europe use of obsidian is recorded from Satani- Dar of Armenia, where Achulian hand-axes are found to be made on obsidian blocks (Semenov, 1964). However, maximum use of obsidian is recorded in various sites of north and South America. The Hopewell mounds in Ohio contained several hundred pounds of obsidian from the Yellowstone area, and obsidian from various sources in California was carried across the Sierra Nevada Mountains and spread far and wide across the region. In the more advanced cultures of Mesoamerica, specialist knappers made millions of blades and other artifacts on an industrial scale, and trade and control of the obsidian sources was a factor in the rise and fall of cities (Whittaker, 2009).

Chalcedony

Chalcedony is made up of micro-crystals of quartz, as is flint. It seems that chalcedony differs from flint and chert either because it has smaller inter-crystalline pores and thus less water content, or because its crystals grow in bundles of radiating fibres rather than forming grains. Chalcedony has different varieties, which are known as Cherysoprase, Carnelian, Quartzine and Sapphirine etc. The rock has hardness 7 in the hardness scale of Mohs and has specific gravity 2.65. The rock also has different colour and opaque in nature. When fractured the rock gives flat conchoidal fracture and produces very sharp and thin edge. In nature chalcedony occurs as crust in kidney shaped lumps or spherolites forming in the voids of veins or fissures in magmatic rocks (Semenov, 1964; Whittaker, 2009).

The use of chalcedony as lithic raw materials started from Paleolithic times in different countries, but in India use of chalcedony is mainly found during Mesolithic times. A number of important Mesolithic sites of central India, like Bhimbetka rock shelter complex, Adamgarh rock art site, Baghor of Madhya Pradesh and Madaha of Uttar Pradesh have evidence of chalcedony as major raw material for production stone tools (Chakrabarty, 2009).

Agate

Agate belongs to the quartz group of rocks. It has several varieties like sardonyx, carneolonyx etc. This variety of rocks has specific gravity 2.5-2.7 and hardness is 7 in Mohs scale. Colour of this group of rocks varies a lot; it may be opaque, dull sheen or mat. When fractured it produces flat conchoidal fracture, like chalcedony produced flakes are thin and very sharp. On a fractured or polished surface horizontal or concentric rings or lines of different colors are visible. Due to the presence of these rings or lines agate is sometimes known as ‘banded agate’. In nature agate is formed in many effusive rocks (usually lavas that have flowed). In natural condition agate is found in condensed condition in almond shaped or larger forms (geodes) within igneous rocks (Semenov, 1964).

The use of agate is usually found during Mesolithic times. In India use of agate as raw material is mainly found in Mesolithic sites of central part of India like Adamgarh rock art site (Chakrabarty, 2009). Sometimes it is also found that agate has been used as semi-precious stone and used in making stone beads in early historic and historic times.

Chert and Flint

Chert and flint are very similar material. However some archaeologists and petrologists tried to find out a distinction between these two rocks but sometimes these diiferences are very confusing. It is found that chemically and structurally chert and flint are essentially the same. Both of these rocks belong to the quartz group of rock with hardness 6-7 in Mohs scale and have specific gravity 2.37-2.67. Beside silicon dioxide these rocks contain traces of sand clay and other materials. Colour ranges from dark grey to greenish and sometimes pinkish. Cherts and flints are usually found as nodules or beds that form as secondary deposits in rocks that are mostly composed of calcium carbonate- that is lime stome and chalks. Most nodules have a rough and often calcareous surface called ‘cortex’. The finest flints and cherts have conchoidal, smooth and almost glassy fracture surface, but still are good and tougher than obsidian or volcanic glass (Semenov, 1964; Whittaker, 2009).

Cherts and flints are extensively used from Lower Paleolithic times to Neolithic times in European Countries. In Neolithic Europe, a number of flint mines were present, where from flint nodules were extracted probably on a economic basis. In India use of flint is not found however, chert has been used by the Mesolithic people on an enormous amount. Almost all microlithic sites of eastern part of India bring forward evidences of the use chert as a primary source of raw material for lithic tools. Important Mesolithic sites of central India like ChopaniMando, SaraiNaharRai and Mahadaha have evidences of the use of chert on an extensive basis (Chakrabarti, 2009).

Jasper

Jasper is a quartz group of rock with a hardness 7-6.5 in Mohs scale. In general the rock contains 70-73 percent of pure quartz, the remaining part being admixture of clay and oxides of iron which gives jasper its varied colours (straw-yellow, olive, cherry red, grey, rapsberryetc). Rarely banded or spotty jaspers are found. This rock gives a rough conchoidal fracture with mat surface, which is almost rough. Flakes are therefore irregular and technically worse than flint and chert. In nature jasper is usually found in the rock deposits of Paleozoic origin (Semenov, 1964). Use of this rock type is found in Paleolithic period of central Asia and neolithic times of several countries. In India few Mesolithic sites present evidences of the use of Jasper.

Quartzite

The traditional definition of quartzite tells us that this rock type is metamorphosed sandstone which fractures through individual grains rather than around them. This fracture quality is a consequence of the crystallographic reorganization and induration of the entire original sand stone (Ebright, 1987:29). Quartzite can be of two different types, one is sedimentary variety and the other is metamorphosed variety. Sedimentary quartzites with its specific characteristics are termed as Orthoquartzites, whereas metamorphic varieties of quartzites are known as Metaquartzite. Both of these quartzite varieties can produce good conchoidal fracture and prehistoric people used both varieties of quartzites to make their tools (Ebright, 1987).

Orthoquartzites referred to the quartz sand stones, where the individual grains of the rock and their matrix works as a single homogeneous solid. On the basis of its maturity or cementation of the sand grains orthoquartzites can be divided into three varieties. In the first variety secondary overgrowth of the quartz has occurred on the original sand grains in crystallographic continuity. As a result of this, an entire sand grain gradually increases in its size. In this type also the opal or chalcedony cement is still the bonding agent of the enlarged sand crystals. In the second variety of orthoquartzites the sand grains have grown in such a way that they formed an interlocking aggregate of individuals and here no cementation is needed as a bonding agent. The third variety is known as ‘pressolved’ quartzite. In this variety due to the increased pressure in rock formation process the solubility increases at the contact point of each sand grains. The end result is the enlarged border area of each sand grain with sutured grain boundary, a high degree of compaction and homogenization of the grain (Carozzi, 1960; Skolnick, 1965; cited in Ebright, 1987).

Metaquartzites contain >90% of quartz and are derived from quartz rich sand stone or chertprotoliths. The difference in the formation of Orthoquartzites and Metaquartzite lies in true metamorphism of the sand stone, which is present only in Metaquartzite. In the transformation of quartz sandstones to Metaquartzite, recrystallization, pressure solution and intracrystalline plastic deformation mechanisms produce interlocking quartz grain structure that produce granoblastic texture. Beside this the grains of Metaquartzite produce a series of deformation features like elongation or other distortion of the grain morphology, the presence of strain marks and the presence of grains which undergo intense undulose extinction- an optical effect seen in petrographic microscope and indicates a distortion in the original crystal lattice (Ebright, 1987; Hefferan and O’Brien, 2010).

Regarding the use of quartzite in prehistoric time it can be said that tools made on quartzite are known from the earliest hominid levels, e.g from Omo and Olduvai Gorge of Africa. Following Semenov (1964:34) it can be said that Paleolithic people used quartzite as primary raw material to make their tools in those countries where flint was absent or was scarce. Uses of quartzite raw material in lower Paleolithic times are mainly found from African and Asian countries where flint is not available, in contrast to Europe. Earliest evidence of the use of quartzite dates back to the Oldowan industry of Africa, the earliest known lower Paleolithic industry of the world. Evidences of the use of cobble and pebble sized quartzite raw materials by prehistoric knappers for making their tools are found (Mishra, 2008).

In India use of quartzite as raw material is found from a number of lower Paleolithic sites. However throughout the Indian subcontinent use of raw materials for making lower Paleolithic tools varies according to the geology of the area. As a result use of quartzite as primary raw material is mainly found in the lower Paleolithic sites of Eastern and parts of the Central and Western India, where this variety of rock is available (Mohapatra, 1962; Ghosh, 1966, 1970; Jacobson, 1975; Mohapatra, 1981; Ghoshet al, 1991; Chauley, 2008; Gaillard et al, 2008).

Diorite

This group of rock contains little quartz or none at all. Basic mineral constituent is feldsper (75 %) and also contains hornblande, augite and sometimes black mica (biotite). Hardness of this group of rock ranges from 6-6.5 in Mohs scale with specific gravity 2.8-2.85. The rock is grey, dark grey or greenish grey in colour, due to this sometimes this rock is known as green stone. When fractured the rock gives feeble conchoidal fracture and rough fractured surface with small or fine grains. In nature the rock is usually found in rocky outcrops of igneous origin. Usually used by Paleolithic people where other rocks are absent, for example lower Paleolithic of Central Asia has evidences of use of this rock type. During Neolithic this rock was used in plenty for its toughness and grounded axes and adzes were used from this raw material (Semenov, 1964).

Rhyolite

It is magmatic rock of tertiary origin or post-tertiary origin. It contains quartz, but its basic constituent is feldsper. Hardness of this rock is 6 in Mohs scale and specific gravity is 2.3-2.7. Colour ranges from white to grey, sometimes with yellow and red specks. The rock usually gives conchoidal fracture and the fractured surface gives dull sheen with rough uneven surface. Like basaltic rocks it occurs in the outcrops of volcanic rocks. Rhyolite was used by the Mesolithic people of south-east Asia and other countries (Semenov, 1964). The Mesolithic sites of West Medinipur and Purulia districts of West Bengal, India have evidences of extensive use of this raw material for the production of lithic artifacts (Basak, 2008).

Basalt Group of Rocks (Trap, Dolerite, Metadolerite)

These are young magmatic rock of igneous origin. Feldsper and pyroxene are the basic component of this group of rock and present of quartz is absent. These rocks have hardness 6-6.5 with specific gravity 2.6-3.11. Usually these rocks are black or dark grey in colour. Among these group of rocks Metadolerite or altered basalt is important in Indian context, so a brief description of these rocks are given below.

The term ‘Metadolerite’ refers to the variably altered dolerite rocks. In general it can be said that Metadolerite is a type of volcanic rock, which can be broadly classified within the Gabbroic group of rocks. It is mentioned earlier that this rock is an altered form of dolerite. Therefore some general features of dolerite can be seen within Metadolerite. Regarding dolerite it can be said that it is an igneous rock with grain size intermediate between basalt and gabbros. In general appearance its colour is dark. It has high specific gravity. Mineral compositions include pyroxene and feldspar, which can be recognized in the weathered parts of the rock. Texturally the rock is medium or fine grained and feldspar laths occur in a criss-cross fashion in it. Optical and mineralogical feature of dolerite indicates that it consists of plagioclase1, pyroxene2 and opaque minerals, often with ophitic3 texture. However optical feature of Metadolerite shows that it may contain small phenocrysts of much altered plagioclase and pyroxene. The other principal mineral of dolerite includes quartz, hornblende, nepheline, olivine etc. Dolerite can be classified on the basis of the presence of major mineral component within it, for example if olivine is present the rock may be called olivine dolerite. If quartz is present it can be called as quartz dolerite etc. Now a day’s dolerite is considered to be synonymous with Diabase and Microgabro (Mukherjee, 1986; Le Maitre, 2002; Ochet al, 2007; Gill, 2010).

Hardness of dolerite is similar with other basalt group of rocks, and it scores within 7-8 in the Moh’s scale of hardness. In general it can be said that Metadolerite and dolerite are both quite hard rock, which gives conchoidal to flat conchoidal fracture. Due to its extreme hardness the rocks were not profoundly used during prehistoric times. Use of dolerite and other basaltic or other form of tough igneous rocks are mainly found during Neolithic and usually various ground and polished wood working tools were made on it.

Use of altered basalt (Mishra et al, 2009) and more specifically dolerite (Corvinus, 1968, Mishra, 1986) are found in many lower Paleolithic sites of southern India or Deccan plateau. However, due to rapid weathering of basaltic rocks some of these sites present degenerated tools and also some sites simply could not be identified or have survived till now because of disappearance of basaltic tools due to rapid weathering (Mishra, 1982:110). In the eastern part of India some scholars reported a few lower Paleolithic tools made on basaltic rocks (Ghosh, 1970, 1991) and more specifically on dolerite (Mohapatra, 1962:93). However, occurrences of tools made on basalt are very few when compared with those made on quartzite. One reason may be the easy availability of suitable raw material like quartzite in this part of India, and the other reason may be the rapid decay of tools made on altered  basalt than those of quartzite (Mishra, 1982). As a result of this except for some exceptional cases tools made on altered basalt and dolerite could not survive, whereas tools made on quartzite could survive. The above list far from exhausts the whole range of rocks and minerals, that were used by prehistoric people to make there tools. The list should also include rocks and minerals like zade, siliceous tufa, siliceous lime stone, fossil wood, haematite nodules, iron stone etc. However, despite its limitation the above list gives a preliminary understanding regarding vastness natural resources like rocks and minerals, used by the prehistoric people for their survival and also gives some ideas regarding adaptive strategy of Stone Age communities in different geographical and environmental settings.

4. Lithic Raw Material Procurement Strategies:

Study on the raw material procurement strategy of prehistoric people, i.e. observations concerning the provenance of raw material, their availability, abundance, use etc. may result not only in the analysis of stone age economic system but also in the development of the behavioral perspectives. Even it is also observed that study of raw material procurement system of the prehistoric people may give fruitful answers regarding questions of territories, zones of influence, exchange and social interaction of past people.

Analysis of the raw material procurement strategies of prehistoric communities can be done following three different steps of study (Inizan et al, 1999), they are- Provenance of raw material, Local availability of raw material and Transport of raw material to the camp site. Brief descriptions of these different stages are given below.

In the study of provenance of raw material an archaeologist has to find out correct source of raw material in a region. In this context it is mentionable that a single region may yield both numerous and varied deposits of raw material source. It is worth mentioning that raw material accessibility may have varied through time, depending on the changing landscape. So the main task of an archaeologist is to trace the accurate sourcing of raw material of past people; it helps him to understand the lithic raw material procurement territory of various prehistoric group of the region. The next step is the assessment of the methods of procurement, such as surface collection, mining, outcrop quarrying, etc.

Understandings on the local availability of raw material may give archaeologists possible explanations regarding nature of the lithic tool types and tool making techniques moreover regarding tool types of the preliminary stages of lithic reduction strategy. Next to this stage comes transport of raw material to the camp site. In this stage of study major emphasis are posed on the understanding of the condition of raw material, when they were transporting to the prehistoric camp sites. Here, archaeologists try to answer some initial questions like was the raw material transported as unworked or initially roughed out blocks? Were the preforms and/or cores prepared at the source itself? Were the tools produced at the site or were they fashioned elsewhere and then subsequently transported as end-products? Partial answers can be given to these questions by examining the artefacts with an eye for technology: by assessing, for instance, the proportions of cortical surfaces or the relative quantities of characteristic debitage and bifacial-knapping waste products, and above all by refitting.

There are many ways in which the transport of raw materials to campsites can be theoretically contemplated, of which four are here considered:

A – The material is brought to the campsite in its more or less original unworked condition(unmodified or tested by just one or two removals) ;

B – The material is brought to the campsite as prepared cores (unflaked) and/or roughouts of bifacial pieces (unfinished);

C – Only unretouched debitage products and/or preforms of bifacial pieces are brought to the campsite;

D – Only the tools (whether retouched or not) and the finished bifacial pieces are brought to the campsite.

Each of these possibilities or “strategies” can be detected when conditions allow, and can be plausibly suspected in almost all major archaeological excavations and explorations (Inizan et al, 1999).

Summary

•  The term ‘Lithic Raw Materials” refers to the stones, rocks or other form of hard minerals, available naturally, which were used by the prehistoric peoples to make artifacts.
• Reasons behind using stone as primary raw material for tool making are that it is very hard and able to produce sharp working edges when fractured.
•  Quality or properties of lithic raw materials include- extreme hardness, Isotropy or glassy character and ability to produce conchoidal flake.
•  Prehistoric people selected specific rocks or minerals as raw material for stone tools only on the basis of the fracture property of the raw material (rocks which can produce Conchoidal fracture).
•  Beside this typical fracture property the lithic raw material must be elastic but brittle, and homogeneous both in crystalline structure (amorphus or crypto-crystalline) and in lacking cracks, inclusions and other flaws.
•  The study of rocks in archaeology is based mainly on chemical, physical, geologic, and mineralogic investigation; this entails identifying the composition of the stone, characterizing its structure and other physical properties, and elucidating the changes that it may have undergone since it was created or last used.
•  Beside the geochemical and geophysical methods of identification of lithic raw materials fracture properties of various rocks must be known by the archaeologists for understanding variation in lithic tools as well as for understanding typo-technological attributes of lithic artifacts.
•  The important rocks, used by the prehistoric people for making majority of their tools belong to mainly one mineral group, the quartz group of rocks, which have a single chemical constituent, SiO2 (Si 46.7 percent, O 53.3 percent), and a number of important physical characteristics in common.
• Varieties within the group have important differences in colour, lustre, fracture properties, specific gravity, external shape and size, origin, occurrence, impurities, transparency and other  features. But these differences are overshadowed by a few qualities in common. Of these an important one is the extreme hardness, an average of 7 on the 10 degree scale of Mohs.
•  An essential quality of many varieties of quartz, which determined its choice by man was isotropism (glassy quality), that is completely uniform physical properties in all directions, as opposed to crystalline rocks.
•  Beside quartz group of rocks few rocks of igneous rocks like Basalt, Diorite etc. were also used by the prehistoric people to make their tools. A basic constituents of these groups of rocks is Feldsper.
•  Type of rocks used by the prehistoric people varies from the Basalt to Quartzite to Obsidian. Even semi-precious rock like Agate, Nephrite and Jade were also used by the prehistoric people to make their tools.
•  Besides understanding of the Petrological and Minerological properties rocks archaeologists also try to understand lithic raw material procurement strategies of prehistoric people.
•  Study on the raw material procurement strategy of prehistoric people may result not only in the analysis of Stone Age economic system but also in the development of the behavioral perspectives.
•  Analysis of the raw material procurement strategies of prehistoric communities can be done following three different steps of study, they are- Provenance of raw material, Local availability of raw material and Transport of raw material to the camp site.
•  Study of raw material procurement system of the prehistoric people may give fruitful answers regarding questions of territories, zones of influence, exchange and social interaction of past people.