This metal was probably one of the first metals to be produced by man because it is highly malleable, easy to smelt and work with. The earliest lead beads are reported from Catal Hüyük (Turkey) dated as 6400 BC. Its first written mention as "abaru" is on Babylonian tablets found in the library of Assyrian king Ashurbanipal (668-626 BC). Alchemists also thought lead to be the oldest metal associated with Saturn. Romans used it for making iron pins to hold large stone blocks for buildings. Artifacts made of lead are found at Harappan (2600-1900 BC) sites of Indus Valley Culture. Ancient Indians possessed the knowledge of mining, metals and alloys; the literary evidence of which is evidenced in Kautilya's ‘Arthsastra’, a treatise on mining and metals written in about 400 BC.
Chemical symbol of lead ‘Pb’ is derived from Latin ‘plumbum’ for soft metal (originally ‘plumbum nigrum’ for ‘black plumbum’). In other languages it is known as ‘plomb’ (French), ‘piambo’ (Italian), ‘plomo’ (Spanish), ‘lead’ (English), leid (Scotish), ‘lood’ (Dutch, Afrikaans), blei (German), ‘bly’ (Swedish, Norwegian, Icelandic), ‘chumbo’ (Portuguese), ‘svinec’ (Russian), ‘kurgosin’ (Kazakh, Uzbek), ‘olow’ (Polish), ‘olovo’ (Czech, Serbian), ‘luaidh’ (Scotish Gabelic), ‘sorb’ (Farsi), ‘khursum (Turkish), ‘rasas’ (Arabic), ‘namari’ (Japanese), ‘kyu ru’ (Tibetan), ‘mata’ (Maori) and ‘takawo’ (Thai). In Indian languages it is known as ‘sisa’, ‘ranga’, ‘haridra’, ‘seemak’, ‘cheen’, ‘sindhur’ (Hindi/ Sanskrit), ‘eeyam’ (Malyalam) and ‘tipu’ (Pali).
Lead metal is bright bluish-white in color when freshly cut, tarnishes to dull grey when exposed and shows a silvery lustre when melts. It is very soft, ductile and highly malleable metal and poor in electrical conductivity. It breaks with hackly fracture and shows isometric crystal system. It is highly resistant to corrosion, hence, is used for storage of acids. It becomes stronger by adding small amount of other metals. Earth crust shows lead concentration of 13 ppb. Lead is poisonous, hence, is dangerous to human health. It is also the end product of radioactive decay. Lead has several isotopes but four (204Pb, 206Pb, 207Pb, 208Pb) are stable ones, and its common radiogenic isotope of 202Pb has a half-life period of about 53,000 years.
Occurrence of metallic or native lead is very rare. It occurs as ore minerals mostly associated with zinc-cadmium-silver, and some copper ores in varied geological environments and different rock formations. A total of 59 ore minerals of lead are known but the most common are galena (PbS), cerussite (PbCO3), anglesite (PbSO4) and minium (Pb3O4).
Galena is the most important lead mineral and contains about 86.6% lead. Sometimes it contains silver upto 1%, hence, is known as leading silver ore. It shows silver grey colour with a bluish tinge, metallic lustre, 2.5 to 2.75 hardness on Mohs scale, 7.2 to 7.6 specific gravity, sub-conchoidal fracture and lead-grey streak. It occurs in isometric crystal system; often showing octahedral forms. Within the zone of weathering or oxidation, galena alters to anglesite or cerussite. In Ancient Egypt galena was used as ‘kohl’ to be applied around the eyes, to reduce desert glare and repelling insects.
Cerussite, also known as white lead ore or lead-spar, contains about 77.5% lead. It crystallizes in orthorhombic system, and frequently occurs as twinned crystals, granular mass and sometimes in fibrous form. It is colourless, white or with grey/ greenish tinge and shows adamantine and resinous lustre and conchoidal fracture. Its hardness is 3.0 to 3.5, and specific gravity of 6.5. Initially it was used in paints and cosmetics.
Anglesite is an oxidation product of galena showing shades of various colours. It occurs as prismatic (orthorhombic-dipyramidal) crystals and earthy masses. It has hardness of 2.5 to 3.0 and 6.3 specific gravity. It shows brittle to conchoidal fracture and adamantine (in crystals) and earthy lustre.
Minium, also known as ‘red lead’ due to its characteristic red colour, is an oxidation product of other lead minerals. It forms under extreme oxidizing conditions and its presence is indicative of the degree of oxidation. It occurs as crystal aggregates (tetragonal system), granular mass and massive form; and shows uneven fracture, orange yellow streak and greasy to adamantine lustre. Its hardness is 2.5 to 3 and specific gravity 8.9 to 9.2.
To extract lead metal, the ores are crushed and concentrated by forth flotation process to 70% or more. The sulphide ores are roasted to convert it to lead oxide, which is then reduced in coke-fired blast furnace. Here, the lead gets converted to metallic form. To make it more pure the melted lead is treated in reverberatory furnace with air, steam and sulphur, where contaminates get oxidized. These are removed by drossing process wherein these float at the top and are skimmed off. The leftover lead contains significant amount of silver which is removed by pyrometallurgical ‘Parkes process’ by adding zinc. Zinc is immiscible with lead and silver is 300 times more soluble in zinc than in lead. Hence, when zinc is added to liquid lead, the silver migrates into zinc. Zinc remains in a separate layer, so it is easily removed. The zinc-silver solution is then heated until the zinc volatilizes, leaving behind the silver.
World smelter production of lead (both primary and secondary) is around 7 Mt per annum. China (23%) followed by the United States (20%), Germany (5%) and the United Kingdom (5%) are the world's largest smelter producers of lead.
India has 176.8 Mt recoverable reserves of lead-zinc ore as on April 2000. It accounts for 2.38 million tonnes of lead metal. The life index of the recoverable ore is nearly 40 years. During 2007-08, the production of lead concentrates at 126 thousand tonnes, increased by 17% over the previous year. Average metal content in the lead concentrate was 61.74% Pb. Rajasthan State accounted for the entire production of lead concentrate during 2007-08. HZL is the leading lead-zinc producing company in India, which has several lead-zinc mines and smelters.
The important lead-zinc deposits of India include Rampura-Agucha (Bhilwara district), Rajpura-Dariba and Sindesar (Rajsamand district), Zawar (Udaipur), Sawar and Kayar-Ghugra (Ajmer district), Basantgarh and Deri (Sirohi district) in Rajasthan; Amba Mata (Banaskantha district) in Gujarat; Buniyar (Baramula district) in Jammu and Kashmir; Rangpo and Pachekhani (East district) in Sikkim; Rupa-Shergaon (West Kameng district) in Arunachal Pradesh; Sargipalli (Sundargarh district) in Orissa; Mamandur (South Arcot district) in Tamil Nadu; Bandalamottu, Dhukonda (Guntur district) and Zangamrajupalle (Cuddapah district) in Andhra Pradesh; Imalia (Jabalpur district) in Madhya Pradesh; Askot (Pithoragarh district) in Uttar Pradesh; and Gorubathan (Darjeeling district) in West Bengal. Currently lead is produced by HZL alongwith zinc at Zawar (located in Aravalli rocks), Rampura-Agucha, Rajpura-Dariba and Sindesar (located within cover sequences in BGC) mines in Rajasthan; Sargipalli mine in Orissa and Agnigundala mine in Andhra Pradesh.
Lead is the main constituent of lead-acid batteries and is widely used as a coloring agent in stained glasses for reducing the radiation transmission. Because of its high specific gravity it is used as fishing sinkers and in balancing wheels of vehicles. It is also used in polyvinyl chloride (PVC) plastic for coating the electrical metal wires, and for shielding from radiation in x-ray laboratories. In electronics its use as soldering agent is well known. Molten lead is used as a coolant in lead-cooled fast reactors. It is the traditional base metal of organ pipes, mixed with varying proportions of tin to control the tones. Sheet-lead is used for sound proofing system. Lead has many applications in building constructions e.g. sheets as architectural metals in roofing, cladding, flashings, gutters and joints, etc. It is well-known that lead was used as water proofing media (17th century) in Rajsmand Reservoir located in Udaipur district, Rajasthan.
Lead-based semi-conductors such as lead telluride, lead selenide and lead antimonide are being used in photovoltaic (solar) cells and infrared detectors. It is still used in making sculptures. Tetra-ethyl lead is used as anti-knock material in aviation fuel for aircrafts. Lead is added to brass to reduce machine tool wear.
It is worth mentioning here that the archaeo-metallurgical survey conducted in Agucha lead-zinc mine area by Craddock et al. (1989) revealed small cupels, some with tuyere, tuyere pieces and small clay pillars with flat bases and concave tops. Silver-rich lead was smelted in open hearth and air is blown across at 900 -1000°C. Unoxidised silver floats on the surface of dense litharge. They also observed that the slags are low in lead (1-2%) and silver (10-100 ppm) in comparison to contemporary Greek and Roman slags (with 100-200 ppm Ag). It shows that Indian metallurgical techniques of those periods were much improved. Native silver is reported from Zawar area; it is noted that rich galena is invariably associated with old working zones, indicating that the ancient miners were interested in rich galena lodes, most likely for silver.
Arthashastra, written in 4th century BC by Kautilya, the Principal Minister of Mauryan Empire (321-296 BC), described various ores of gold, silver, lead, zinc and copper and smelting processes. Archaeological studies of Rampura-Agucha area showed the old mining activities of Pre-Mauryan to Gupta period, which support the above. Dating of material from lead-zinc mines of Zawar, Rajpura Rajpura-Dariba and Agucha was conducted by researchers from British Museum, Hindustan Zinc Limited and Baroda University. The oldest dates of charcoal from these mines indicated that the mining activites are very old i.e. 2410 ± 100 BP (Zawar Mala), 2350 ± 40 BP (Agucha) and 3040 ± 150 BP (Rajpura-Dariba) in Rajasthan.
Open cast lead-zinc mine of Rampura-Agucha, Bhilwara district, Rajasthan
The 2350 years old wooden revetment used for holding the hanging wall, Rajpura-Dariba area, Udaipur district, Rajasthan
Open cast lead-zinc-copper mine of Amba Mata, Banaskantha district, Gujarat
Ancient underground lead-zinc mine of Zawar area, Udaipur district, Rajasthan
A galena weight still in use in Angoriya prospect area, Chittaurgarh district, Rajasthan
An isometric crystal of galena from Zawar area
An old lead-zinc working in Kayar-Ghugra area, Ajmer district, Rajasthan
Compiled by : A.K. GROVER, Director GSI, WR, Jaipur-302004
This website belongs to the Geological Survey of India, Ministry of Mines, Government of India. Site is best viewed in 1024x768 resolution
Disclaimer: Endeavour has been made to make available updated, correct and accurate information. The errors, if any, whenever brought to notice will be rectified. But, the Ministry/Department will accept no responsibility and liability, of whatever nature, for the correctness of the material on website. In this regard, the users are advised to verify, in their own interest, the correctness of the facts from the concerned official or person.
