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Mineralogy (Samskrit: धातुशास्त्रम्) or metallurgy discusses the chemistry of Dhatus (minerals), their properties, composition, reactions, combination products namely alloys and their uses. A related topic, mining of metals, involves the chemistry of extraction from ores, smelting and forging activities. History of mining in the Indian subcontinent can be traced back to pre-Harappan period where the evidence of earliest settlements of farming communities using metal implements have been found.<ref name=":0">Singh. R. D, (1997) ''History of Technology in India, Vol. 1, From Antiquity to c. 1200 A.D. by A. K. Bag.'' New Delhi: Indian National Science Academy. (Chapter Mining: Page 48 - ) </ref>  

Mineralogy (Samskrit: धातुशास्त्रम्) or metallurgy discusses the chemistry of Dhatus (minerals), their properties, composition, reactions, combination products namely alloys and their uses. A related topic, mining of metals, involves the chemistry of extraction from ores, smelting and forging activities. History of mining in the Indian subcontinent can be traced back to pre-Harappan period where the evidence of earliest settlements of farming communities using metal implements have been found.<ref name=":0">Singh. R. D, (1997) ''History of Technology in India, Vol. 1, From Antiquity to c. 1200 A.D. by A. K. Bag.'' New Delhi: Indian National Science Academy. (Chapter Mining: Page 48 - ) </ref>  

Bharatavarsha is known for its use of gold and silver for jewelry and making ornamental vessels for domestic use with silver. Copper tools, such as axes, sickles are found in many archaeological sites indicating that many farming tribes and agricultural communities were using them. Metallurgy of copper and its alloys (brass and bronze) was highly developed during this period. A remarkable use of brass was made in the constructional work of an unfinished Vihara made near Nalanda (Bihar). Thus many archaeological revelations have unearthed valuable knowledge pertaining to sulbashastra (geology) and dhatushastra (metallurgy) of the ancients.<ref name=":0" />  

Bharatavarsha is known for its use of gold and silver for jewelry and making ornamental vessels for domestic use with silver. Copper tools, such as axes, sickles are found in many archaeological sites indicating that many farming tribes and agricultural communities were using them. Metallurgy of copper and its alloys (brass and bronze) was highly developed during this period. A remarkable use of brass was made in the constructional work of an unfinished Vihara made near Nalanda (Bihar). Thus many archaeological revelations have unearthed valuable knowledge pertaining to sulbashastra (geology) and dhatushastra (metallurgy) of the ancients.<ref name=":0" /> [[File:Sushruta's Surgical Tools Made of Iron.PNG|thumb|Ancient Surgical tools in India|500x500px]]

 

== Introduction ==

== Introduction ==

Metals, Minerals and ores are mentioned by the terms dhatu (धातुः) khanija (खानिजम्) and the chemistry involved is termed Khanija-rasayana (खानिजरसायनम्). A mineral is defined in modern terms as follows<ref name=":1">''[http://eprints.nmlindia.org/5802/1/1-24.PDF Minerals and Their Exploitation in Ancient and Pre-modern India]'' by Prof. A. K. Biswas</ref><blockquote>''"As we knew mineral is a naturally occurring crystalline element or a compound having definite chemical composition, and formed as a product of inorganic processes."''</blockquote>The scientific analysis of the archaeological and literary evidences points to the debunking of the aryan invasion myth in the recent times.<ref name=":1" /> <blockquote>''A number of experts have concluded that the collapse of the Harappan civilization was not on account of any 'foreign invasion' but essentially due to repeated floods, tectonic movement leading to the drying up and disappearance of the Sarasvati river, civil war, loss of trade etc.''</blockquote>Just like pottery, metals in antiquity is also linked to the history of a civilization. In the ancient past, the first metals to be utilized were those found in the native or elemental state, and then progressively those metals were used which could be easily extracted or smelted from their ores. The smelting of metals, which were more difficult to extract from ores, was mastered later. Most of the metals and elements indicated in the Periodic Table were in fact identified only in the last few centuries.   

Metals, Minerals and ores are mentioned by the terms dhatu (धातुः) khanija (खानिजम्) and the chemistry involved is termed Khanija-rasayana (खानिजरसायनम्). A mineral is defined in modern terms as follows<ref name=":1">''[http://eprints.nmlindia.org/5802/1/1-24.PDF Minerals and Their Exploitation in Ancient and Pre-modern India]'' by Prof. A. K. Biswas</ref><blockquote>''"As we knew mineral is a naturally occurring crystalline element or a compound having definite chemical composition, and formed as a product of inorganic processes."''</blockquote>The scientific analysis of the archaeological and literary evidences points to the debunking of the aryan invasion myth in the recent times.<ref name=":1" /> <blockquote>''A number of experts have concluded that the collapse of the Harappan civilization was not on account of any 'foreign invasion' but essentially due to repeated floods, tectonic movement leading to the drying up and disappearance of the Sarasvati river, civil war, loss of trade etc.''</blockquote>Just like pottery, metals in antiquity is also linked to the history of a civilization. In the ancient past, the first metals to be utilized were those found in the native or elemental state, and then progressively those metals were used which could be easily extracted or smelted from their ores. The smelting of metals, which were more difficult to extract from ores, was mastered later. Most of the metals and elements indicated in the Periodic Table were in fact identified only in the last few centuries.   

Chandogya Upanisad recognised that metals have intrinsic properties irrespective of the shapes that these may assume (Cha. Up 6.1.5 & 6). It stipulated that one can join gold with the help of borax, lead with the help of tin 'etc.<blockquote>तद्यथा लवणेन सुवर्णँ सन्दध्यात्सुवर्णेन रजतँ रजतेन त्रपु त्रपुणा सीसँ सीसेन लोहं लोहेन दारु दारु चर्मणा ॥ ७ ॥ (Chan. Upan. 4.17.7)<ref>Chandogya Upanishad ([https://sa.wikisource.org/wiki/%E0%A4%9B%E0%A4%BE%E0%A4%A8%E0%A5%8D%E0%A4%A6%E0%A5%8B%E0%A4%97%E0%A5%8D%E0%A4%AF%E0%A5%8B%E0%A4%AA%E0%A4%A8%E0%A4%BF%E0%A4%B7%E0%A4%A6%E0%A5%8D/%E0%A4%85%E0%A4%A7%E0%A5%8D%E0%A4%AF%E0%A4%BE%E0%A4%AF%E0%A4%83_%E0%A5%AA Adhyaya 4 Khanda 17])</ref></blockquote>Summary: Just as one would join together (pieces of) gold by borax, by gold silver, by silver tin, by tin lead, by lead iron, by iron wood or by leather.<ref>Mm. Ganganath Jha. (1923) ''Chhandogya Upanishad and Sri Sankara's Commentary.'' Madras: The India Printing Press. (Page 261)</ref>

Chandogya Upanisad recognised that metals have intrinsic properties irrespective of the shapes that these may assume (Cha. Up 6.1.5 & 6). It stipulated that one can join gold with the help of borax, lead with the help of tin 'etc.<blockquote>तद्यथा लवणेन सुवर्णँ सन्दध्यात्सुवर्णेन रजतँ रजतेन त्रपु त्रपुणा सीसँ सीसेन लोहं लोहेन दारु दारु चर्मणा ॥ ७ ॥ (Chan. Upan. 4.17.7)<ref>Chandogya Upanishad ([https://sa.wikisource.org/wiki/%E0%A4%9B%E0%A4%BE%E0%A4%A8%E0%A5%8D%E0%A4%A6%E0%A5%8B%E0%A4%97%E0%A5%8D%E0%A4%AF%E0%A5%8B%E0%A4%AA%E0%A4%A8%E0%A4%BF%E0%A4%B7%E0%A4%A6%E0%A5%8D/%E0%A4%85%E0%A4%A7%E0%A5%8D%E0%A4%AF%E0%A4%BE%E0%A4%AF%E0%A4%83_%E0%A5%AA Adhyaya 4 Khanda 17])</ref></blockquote>Summary: Just as one would join together (pieces of) gold by borax, by gold silver, by silver tin, by tin lead, by lead iron, by iron wood or by leather.<ref>Mm. Ganganath Jha. (1923) ''Chhandogya Upanishad and Sri Sankara's Commentary.'' Madras: The India Printing Press. (Page 261)</ref>

It is interesting to note that ancient texts have mentioned many matters regarding the existence and usage of metals, their properties, nature and their extraction. Debiprasad Chattopadhyaya acclaimed [[Uddalaka (उद्दालकः)|Uddalaka Aruni]] as ''''the first scientist in the world'''<nowiki/>'. Uddalaka Aruni as mentioned in the Chandogya Upanishad propounded that everything in the universe including man evolved out of three elements, and even mind is a product of matter. According to Chattopadhyaya Maharshi Uddalaka preceded Theles of Greece by nearly two centuries.<ref name=":1" /><ref>Chattopadhyaya, Debiprasad. (1991) ''History of Science and Technology in Ancient India ll Formation of the Theoretical Fundamentals of Natural Science.'' Calcutta: Firma KLM Pvt. Ltd., </ref>

It is interesting to note that ancient texts have mentioned many matters regarding the existence and usage of metals, their properties, nature and their extraction. Debiprasad Chattopadhyaya acclaimed [[Uddalaka (उद्दालकः)|Uddalaka Aruni]] as ''''the first scientist in the world'''<nowiki/>'. Uddalaka Aruni as mentioned in the Chandogya Upanishad propounded that everything in the universe including man evolved out of three elements, and even mind is a product of matter. According to Chattopadhyaya Maharshi Uddalaka preceded Theles of Greece by nearly two centuries.<ref name=":1" /><ref>Chattopadhyaya, Debiprasad. (1991) ''History of Science and Technology in Ancient India ll Formation of the Theoretical Fundamentals of Natural Science.'' Calcutta: Firma KLM Pvt. Ltd., </ref>

== Gem - Minerals ==

== Gem - Minerals ==

=== सुवर्णम् हिरण्यम् वा ॥ Gold (''Aurum'' - Au) ===

=== सुवर्णम् हिरण्यम् वा ॥ Gold (''Aurum'' - Au) ===

Arthashastra describes the qualities of the gold ore thus<blockquote>पीतकास्-ताम्रकास्ताम्र-पीतका वा भूमि-प्रस्तर-धातवो भिन्ना ..... बहुफेनधूमाश्च सुवर्ण-धातवः प्रतीवाप-अर्थास्ताम्ररूप्य-वेधनाः ।। ०२.१२.०५ ।। (Arth. Shast. 2.12.5)<ref name=":6" /></blockquote>''"Those ores which are obtained from plains or slopes of mountains; which are either yellow or as red as copper or reddish yellow; which are disjoined and marked with blue lines; which have the colour of black beans (masha, Phraseolus Radiatus), green beans (mudga, Phraseolus Mungo), and sesamum; which are marked with spots like a drop of curd and resplendent as turmeric, yellow myrobalan, petals of a lotus, acquatic plant, the liver or the spleen; which possess a sandy layer within them and are marked with figures of a circle or a svastika; which contain globular masses (sagulika); and which, when roasted do not split, but emit much foam and smoke are the ores of gold (suvarnadhátavah), and are used to form amalgams with copper or silver (pratívápárthasté stámrarúpyavedharáh)".''<ref name=":7">Shamasastry. R. Kautilya's Arthashastra with English Translation. (Pages 111 - )</ref>

Arthashastra describes the qualities of the gold ore thus<blockquote>पीतकास्-ताम्रकास्ताम्र-पीतका वा भूमि-प्रस्तर-धातवो भिन्ना ..... बहुफेनधूमाश्च सुवर्ण-धातवः प्रतीवाप-अर्थास्ताम्ररूप्य-वेधनाः ।। ०२.१२.०५ ।। (Arth. Shast. 2.12.5)<ref name=":6" /></blockquote>''"Those ores which are obtained from plains or slopes of mountains; which are either yellow or as red as copper or reddish yellow; which are disjoined and marked with blue lines; which have the colour of black beans (masha, Phraseolus Radiatus), green beans (mudga, Phraseolus Mungo), and sesamum; which are marked with spots like a drop of curd and resplendent as turmeric, yellow myrobalan, petals of a lotus, acquatic plant, the liver or the spleen; which possess a sandy layer within them and are marked with figures of a circle or a svastika; which contain globular masses (sagulika); and which, when roasted do not split, but emit much foam and smoke are the ores of gold (suvarnadhátavah), and are used to form amalgams with copper or silver (pratívápárthasté stámrarúpyavedharáh)".''<ref name=":7">Shamasastry. R. Kautilya's Arthashastra with English Translation. (Pages 111 - 115)</ref>

Early reference to gold is to be found in the Rigveda samhita. However, not many gold artifacts dating to Pre-Harappan period have been reported although in Rgveda Gold and its alloys with Ag and Cu have been mentioned in many places, such as, 1-85.9, 88.5, 67.3; II-37.9; V-54.15, 57.1, 60.4; VIII - 7.27-32 etc. In Vedic literature this metal has been mentioned as Hiranya (हिरण्यम्) probably because of its high corrosion and oxidation resistance and the practice of its preservation through generations.<ref name=":5">Bhanu Prakash (1997) ''History of Technology in India, Vol. 1, From Antiquity to c. 1200 A.D. by A. K. Bag.'' New Delhi: Indian National Science Academy. (Chapter Metals and Metallugy: Page 80 )</ref>

Early reference to gold is to be found in the Rigveda samhita. However, not many gold artifacts dating to Pre-Harappan period have been reported although in Rgveda Gold and its alloys with Ag and Cu have been mentioned in many places, such as, 1-85.9, 88.5, 67.3; II-37.9; V-54.15, 57.1, 60.4; VIII - 7.27-32 etc. In Vedic literature this metal has been mentioned as Hiranya (हिरण्यम्) probably because of its high corrosion and oxidation resistance and the practice of its preservation through generations.<ref name=":5">Bhanu Prakash (1997) ''History of Technology in India, Vol. 1, From Antiquity to c. 1200 A.D. by A. K. Bag.'' New Delhi: Indian National Science Academy. (Chapter Metals and Metallugy: Page 80 )</ref>

Arthashastra describes the qualities of the lead ore thus<blockquote>काक-मोचकः कपोत-रोचना-वर्णः श्वेत-राजि-नद्धो वा विस्रः सीस-धातुः ।। ०२.१२.१३ ।। (Arth. Shast. 2.12.13)<ref name=":6" /></blockquote>''"Those ores which have the colour of kákamochaka (Solanum Indica), pigeon, or cow‟s bile, and which are marked with white lines and smell like raw meat are the ores of lead."''<ref name=":7" />

Arthashastra describes the qualities of the lead ore thus<blockquote>काक-मोचकः कपोत-रोचना-वर्णः श्वेत-राजि-नद्धो वा विस्रः सीस-धातुः ।। ०२.१२.१३ ।। (Arth. Shast. 2.12.13)<ref name=":6" /></blockquote>''"Those ores which have the colour of kákamochaka (Solanum Indica), pigeon, or cow‟s bile, and which are marked with white lines and smell like raw meat are the ores of lead."''<ref name=":7" />

The lead artifacts during the Harappan period reflect the fact that people were acquainted with lead ores (such as galena) and their smelting process which is simple on account of easy reducibility and low melting point of the metal. Like gold and silver, lead did not find extensive usage in tools and implements owing to its softness. It is one of the softest and heaviest metal having shining grey lustre which leaves a black streak on paper.  

The lead artifacts during the Harappan period reflect the fact that people were acquainted with lead ores (such as galena) and their smelting process which is simple on account of easy reducibility and low melting point of the metal. Like gold and silver, lead did not find extensive usage in tools and implements owing to its softness. It is one of the softest and heaviest metal having shining grey lustre which leaves a black streak on paper. It is so soft that it can be scratched even with nail hence it’s use has been mostly for the manufacture of cheap jewellery dies or pattern for shaping other metals, and as a hardner in copper alloys.  

 

It is so soft that it can be scratched even with nail hence it’s use has been mostly for the manufacture of cheap jewellery dies or pattern for shaping other metals, and as a hardner in copper alloys.

==== Extraction Process ====

==== Extraction Process ====

* Gold coating of copper ornaments was very popular

* Gold coating of copper ornaments was very popular

=== रसः ॥ Mercury ===

=== रसः वैकृन्तक वा ॥ Mercury ===

Ore of Mercury: Cinnabar (Hingula)

 

Mercury is a metal that has been of great alchemical importance in ancient times. Ayurvedic texts have presented the science of using mercury, as [[Rasashastra (रसशास्त्रम्)|Rasashastra]].

 

Mercury Ores: Cinnabar (Hingula)

Mercury is a metal that has been of great alchemical importance in ancient times. It is a volatile metal, which is easily produced by heating cinnabar followed by the downward distillation of mercury vapour. Some of the earliest literary references to the use of mercury distillation come from Indian treatises such as the Arthashastra of Kautilya. Ayurvedic texts have presented the science of using mercury, as [[Rasashastra (रसशास्त्रम्)|Rasashastra]].

It is a volatile metal, which is easily produced by heating cinnabar followed by the downward distillation of mercury vapour. Some of the earliest literary references to the use of mercury distillation come from Indian treatises such as the Arthashastra of Kautilya.  

* Sindhur or Vermilion was Cinnabar, mercuric sulphide, was used to make the red/maroon mark on the forehead as described by Charaka.

* Sindhur or Vermilion was Cinnabar, mercuric sulphide, was used to make the red/maroon mark on the forehead as described by Charaka.

[[File:Delhi Iron Pillar.png|thumb|Delhi Iron Pillar " The Rustless Wonder"]]

[[File:Delhi Iron Pillar.png|thumb|Delhi Iron Pillar " The Rustless Wonder"|588x588px]]

=== अयस् ॥ Iron (''Ferrum - Fe'') ===

=== अयस् ॥ Iron (''Ferrum - Fe'') ===

Iron supplemented copper in the preparation of various tools for hunting and agriculture, apart from household objects and building materials. A survey of ancient literature has provided ample evidence that iron and steel making technology and their difference has been known in the Vedic period (based on references in Rgveda and Yajurvedd) and may be even earlier.<ref name=":5" />

Iron supplemented copper in the preparation of various tools for hunting and agriculture, apart from household objects and building materials. A survey of ancient literature has provided ample evidence that iron and steel making technology and their difference has been known in the Vedic period (based on references in Rgveda and Yajurvedd) and may be even earlier.<ref name=":5" />

==== Extraction Process ====

==== Extraction Process ====

* Ores of Iron : Haematite (Fe₂O₃), Magnetite (Fe₃O₄), Goethite (HFeO₂) and Limonite (FeO (OH)_n*H₂O).

* Ores of Iron : Haematite (Fe₂O₃), Magnetite (Fe₃O₄), Pyrite (FeS)

 

Tradition describes the ancient iron making process which was considered a sacred ritual and the secret of smelting process was highly guarded, transmitted only to the younger generation from the family or tribe. Women also had an active role to play and were designated to do specific jobs in the process. The operation was carried out near ore deposit or in the nearby forest to procure the required wood. The whole operation of the furnace can be divided into five parts<ref name=":5" />

# Collection and preparation of the raw-material : Experienced elders located the suitable deposit of the ore after the due rituals and pujas are performed. Women helped in breaking and transporting the ore. Charcoal was prepared from wood like Irool (Xylia dolaberiformis) Teak, Babul (Acacia arbica), Sal (Shorearubusta), Bamboo (Caleotropis gigantica) etc. yielding dense and heavy charcoal. They also maintained the outside of the furnace and stored sufficient quantity of water.

# Ignition of the furnace and its operation : Once the furnace was ignited after the required preparation with charcoal, bellows were operated to raise the temperature at slow pace. When the furnace was red hot and CO gas was seen burning at the top, the furnace was charged with pre-heated ore and charcoal in alternate layers. The preheating of the ore was done by storing it on the inclined platform. As the maximum temperature was achieved at the tuyere level, by increased air blowing, a small hole was made in the front wall to tap out the molten Fayalite slag. The reduced sponge iron gets consolidated in the hearth by partial fusion, the block of which is removed by breaking the front wall of the furnace.

 

In Rasa Ratna Samuccaya and other Ayurvedic text a number of processes have been mentioned for the extraction of iron from Biotite and other iron bearing minerals for the preparation of medicine. This process is known as Satvapaatana, and generally consists of three major steps : (i) Shodhana (purification), (ii) Bhaavana (Maceration and Trituration) (iii) Dhamana (Heating and smelting).<ref name=":5" />

 

 

The carburization of hot sponge or bloom could be done by the following techniques:<ref name=":5" />

# By selective carburization of cutting edge of the implements by the application of carburizing paste and reheating to 950 to l000⁰C.

Rasaratnasamucchaya (70-71 shlokas) has given the following classification of iron-carbon alloys. Based on the characteristic features of the fractured surfaces and other properties such as ductility, magnetism and hardness etc, these have been further classified into sub-groups. This type of classification has no parallel in the world.  

 

'''Surgical tools''' : The Susruta Samhita has mentioned the method of fabrication of more than 100 surgical tools made of Fe-C alloys and the process of heat treatment to obtain razor sharp edge capable of splitting hair into two halves longitudinally.

'''Surgical tools''' : The Susruta Samhita has mentioned the method of fabrication of more than 100 surgical tools made of Fe-C alloys and the process of heat treatment to obtain razor sharp edge capable of splitting hair into two halves longitudinally.

'''Iron Pillar of Delhi''' : The forging of wrought iron seems to have reached its zenith in India in the first millennium AD. The earliest large forging is the famous iron pillar with a height of over 7 m and weight of about 6 tons at New Delhi ascribed to Chandragupta Vikramaditya 400- 450 CE . The inscription of the Gupta period of the 4th century CE is in Brahmi script of Sanskrit (Figure 8).The pillar is believed to have been made by forging together a series of disc-shaped iron blooms. The Iron Pillar, the earliest and the largest surviving iron forging in the world, is regarded as a metallurgical marvel because it has defied the laws of corrosion of iron even after so many centuries, earning the nickname, the ‘rustless wonder’. Its astounding corrosion-resistance is partly due to its composition; high slag and phosphorus (0.25 p.c.) content and low manganese (0.05) and sulphur (0.005) content.<ref name=":1" /><ref name=":4" />

'''Iron Pillar of Delhi''' : The forging of wrought iron seems to have reached its zenith in India in the first millennium AD. The earliest large forging is the famous iron pillar with a height of over 7 m and weight of about 6 tons at New Delhi ascribed to Chandragupta Vikramaditya 400- 450 CE . The inscription of the Gupta period of the 4th century CE is in Brahmi script of Sanskrit (Figure 8).The pillar is believed to have been made by forging together a series of disc-shaped iron blooms. The Iron Pillar, the earliest and the largest surviving iron forging in the world, is regarded as a metallurgical marvel because it has defied the laws of corrosion of iron even after so many centuries, earning the nickname, the ‘rustless wonder’. Its astounding corrosion-resistance is partly due to its composition; high slag and phosphorus (0.25 p.c.) content and low manganese (0.05) and sulphur (0.005) content.<ref name=":1" /><ref name=":4" />

'''Wootz Steel''' : Another iron product of repute is the high carbon steel manufactured in the recent past by the crucible process. Wootz is the anglicized version of "ukku" in the languages of the states of Karnataka, and Andhra Pradesh, a term denoting steel. Literary accounts suggest that steel from the southern part of the Indian subcontinent was exported to Europe, China, the Arab world and the Middle East. Studies on Wootz indicate that it was an ultra-high carbon steel with between 1-2% carbon and was used to make the fabled Damascus swords.

'''Wootz Steel''' : This iron-carbon alloy of repute is the high carbon steel manufactured in the recent past by the crucible process. It is called Wootz Steel, the anglicized version of "ukku" in the languages of the states of Karnataka, and Andhra Pradesh, a term denoting steel. Literary accounts suggest that steel from the southern part of the Indian subcontinent was exported to Europe, China, the Arab world and the Middle East. Studies on Wootz indicate that it was an ultra-high carbon steel with between 1-2% carbon.

* Largest and riches deposits of Hematite and Magnetite all over India

* The Largest and Earliest Rustless Iron Forging Wonder : Iron Pillar of Chandragupta Vikramaditya at Delhi

* The Largest and Earliest Rustless Iron Forging Wonder : Iron Pillar of Chandragupta Vikramaditya at Delhi

* Wootz Steel prepared by indigenous crucible process.  

* Wootz Steel prepared by indigenous crucible process.  

* Monumental Iron pillar at Dhar in Central India, and Kodachadri in coastal Karnataka and Iron beams of the Konark temple.

* Monumental Iron pillar at Dhar in Central India, and Kodachadri in coastal Karnataka and Iron beams of the Konark temple.

=== Zinc ===

=== यशद ॥ Zinc (''Zinc - Zn'') ===

The earliest firm evidence for the production of metallic zinc comes from India. Of the eight metals used in antiquity zinc is one of the most difficult to smelt since it volatalizes at about the same temperature of around 1000 °C that is needed to smelt zinc ore. As a result, it forms as a vapour in the furnace which would immediately get reoxidised and hence the pure form is lost. So there are very few references to metallic zinc in early treatises. In India there is unique evidence for the extensive and semi-industrial production of zinc at the Zawar area of Rajasthan. An ingenious method was devised of downward distillation of the zinc vapour formed after smelting zinc ore using specifically designed retorts with condensers and furnaces. The zinc vapour could be cooled down drastically to get a melt that could solidify to zinc metal. The Rasaratnakara, Nagarjuna describes this method of production of zinc.

Arthashastra does not specifically mention about Zinc ores. Zinc is silvery white in colour and very hard and brittle owing to its close packed hexagonal crystal structure. The earliest firm evidence for the production of metallic zinc comes from India. Of the eight metals used in antiquity zinc is one of the most difficult to smelt since it volatalizes at about the same temperature of around 1000°C that is needed to smelt zinc ore. As a result, it forms as a vapour in the furnace which would immediately get reoxidised and hence the pure form is lost. So there are very few references to metallic zinc in early treatises.  

 

 

In India there is unique evidence for the extensive and semi-industrial production of zinc at the Zawar area of Rajasthan. An ingenious method was devised of downward distillation of the zinc vapour formed after smelting zinc ore using specifically designed retorts with condensers and furnaces. The zinc vapour could be cooled down drastically to get a melt that could solidify to zinc metal. The Rasaratnakara, Nagarjuna describes this method of production of zinc.

* Zawar Zinc mines using downward distillation process to produce metallic zinc.

* Zawar Zinc mines using downward distillation process to produce metallic zinc.

त्रपु ॥ Tin  

 

=== त्रपु ॥ Tin (''Stannum - Sn'') ===

 

 

 

 

 

 

== References ==

== References ==

<references />

<references />