2007: How many dealers, jewelers and consumers actually know where the stones come from? Very few. Only a lucky few have had the opportunity to actually see the working of a mine. The island of Sri Lanka is blessed with virtually all known colored stones in the world, but most dealers, jewelers and consumers focus on high value stones and that's all they know. But the truth is otherwise; Sri Lanka is also a treasure trove for rare stones and the author explains in detail the mining methodology that is good for Sri Lanka with minimum environmental damage.
(via Journal of Gemmology, Vol.28, No.3, July 2002) P.G.R Dharmaratne writes:
Abstract
Various methods of accessing alluvial gem gravels (known as illama) in Sri Lanka for the extraction of gemstones, such as open pits, shafts and tunnels, and dredging, are briefly summarized. The methods adopted to minimize environmental damage caused by mining include: introduction of legislation, restriction on types of mining methods permitted, awareness programmes and restoration of mined-out lands. The lessons learned by the Sri Lankan gem industry, with centuries of experience, can be applied to other gem producing countries.
Introduction
Mining of minerals for the consumption by human beings started many centuries ago and if it were not for minerals and their products, the world would be without many of the material comforts for its population today. For example, life can not be imagined without having metal for machinery and motor vehicles, cement for construction, fuel and minerals for energy production, all of which are products of mining. Gems, though not an essential commodity, on the other hand make life more beautiful and attractive. So it can be said that minerals bring comforts for the body while gems give comfort for the senses and the eye in particular. Since minerals play such an important role in the lives of people, it is the duty of all of us to extract them with least possible damage to the environment in which we live.
Gem mining
Introduction
Sri Lanka has been identified as one of the earliest sources of gems in the world, and is still a leading producer. Mining activities were not properly organized until early 1970s; before 1970, gem mining was done haphazardly and different regulations were in force in different districts. With the establishment of the State Gem Corporation, predecessor to the National Gem and Jewellery Authority, in 1972 all the activities were brought under one institution and many regional offices were established to issue licenses for mining and thereby supervise and minimize the impact on the environment. One of the main objectives of the State Gem Corporation was the development, regulation and control of the gem industry. Mining increased rapidly with provision of many facilities to gem exporters. While legalized mining reduced the damage to the environment, illicit mining also continued and unlike licensed mining, this caused more extensive damage to the environment.
Mining by means of open pits
A gem bearing gravel bed occurring on or near the surface is exploited using mammoties and crowbars to excavate open pits most of which are without any support on their side walls. The miner fills bamboo baskets with grave, and throws them upward to the waiting hands of another man at the pit head. The method used for bailing out water from the pit depends on the rate of water seepage. It can be done by hand with buckets or by using mechanized water pumps. When the gem bearing gravel is reached, it is collected separately at the pit head, and washed in running water in closely woven conical bamboo baskets. If there is a shortage of water, material from surface digging can be dry sieved after removing the larger rocks by hand. Only the remaining material needs to be washed to remove dust and clay. With the correct techniques of washing, gemstones can be concentrated at the bottom of the sieve.
The use of bulldozers and scrapers has been allowed in special circumstances such as where very thin gem gravel beds occur, or in areas which have been mined out by open pits or shafts and tunnels. This machinery is used to remove the overburden, since open pit mining is no longer economical in such situations.
Mining by shafts and tunnels
The placer deposits of gems (illama) and in situ deposits occurring below a certain depth are mined by sinking shafts and excavating tunnels. In Sri Lanka, only placer deposits are mined by sinking pits, but for deeper deposits, recovery of the illama by successively deeper pits becomes uneconomical. In such situations, it is common practice to excavate horizontal tunnels at the level of the gem bearing gravel layer in order to recover gemstones. In small operations through hard ground, the shafts are either round (2m diameter) or square (2m sides), but in soft ground (e.g beneath paddy fields), they are rectangular in section, measuring about 2 x 4m.
The shaft is reinforced with timber crossbeams (from rubber trees0 while fern foliage is pushed between the sides of the shaft and vertical struts (arecanut trunks) are driven behind the crossbeams, to prevent the damp sidewalls from caving in. While shafts are 3-4m deep, clay and sand shoveled into small bamboo baskets are manually lifted up to the shaft head. Deeper shafts utilize manually operated winches to lift excavated material and water. As the rate of water flow increases, traditional methods of removing water are replaced by water pumps.
The illama is collected separately near the shaft at a place where the ground is specially leveled. The illama can be up to a few meters thick, and generally rests directly on decomposed rock (malawa) or unweathered rock (parugala). Washing the illama is done in a nearby stream or in a pond specially constructed for the purpose. The miners stand waist deep in the pond and move the baskets in a circular motion to remove all the lighter materials. Washing is continued for about half an hour with more illama being intermittently fed into the baskets. During the washing, lighter material collects at the top of the basket and is hand sorted and thrown out of the pond, while the heavy gem bearing material settles at the bottom of the basket. After washing, the baskets are stacked. Later, an experienced miner collects the gems while sweeping the gravel back and forth by hand.
When illama is at a fairly deep level (>8m) horizontal tunnels, 1-2m high, are excavated from the bottom of the shaft so that the floor of the tunnel follows or lies on the rock layer underlying the illama. As the tunnels are excavated deeper into the surrounding area, an adequate supply of fresh air and oxygen for breathing as well as for lighting candles, becomes more difficult. In such situations, air pumps are installed to provide fresh air into the mine. The tunnels are supported with timber and crossbeams similar to those of the main shaft. In Sri Lanka, over 60 percent of the mining is done by shafts and tunnels.
River dredging
When the gem bearing placer deposits occur at the bottom of a shallow river, long-handled mammoties (a type of manual scraper with the blade perpendicular to the handle so that material can be scooped up towards the user) are used to scoop up the gravel. To prepare for this process, a brushwood dam is erected at a place where the river slows down naturally, and the water is allowed to escape from one side of the dam. Using long-handled mammoties, the overlying sand and gravel are scooped over the place where water passes through. This procedure is continued until the illama is reached. The illama is then loosened by using long pointed steel rods and is also scooped into the moving water which removes the lighter and finer minerals, leaving heavy gem minerals behind. Good gemstones can be easily seen and hand picked and the rest of the gravel is washed in the same manner as discussed earlier.
In the past, gravel pumps and dredgers could be used to extract the overburden and gem gravel, but they are banned at present because of the damage they cause to river banks.
Environmental management
Causes of environmental damage
Damage to the environment due to gem mining has been discussed by de Silva (1989), Rupasinghe and Cooray (1993) and Dharmaratne (1994).
1. Damage to land and vegetation cover
Most damage to land caused by mining activities is due to open-pit methods. In particular, mining for topaz involves large volumes of earth to recover gemstones. Illicit miners leave behind larger craters and pits, particularly in the forests, which fill with water and become breeding grounds for mosquitoes; this in turn endangers the lives of people and animals.
Tree trunks are used to support the walls and roofs of shafts and tunnels and the flow of earth into the workings is prevented by lagging with variety of fern (kekilla). This fern has strong roots which bind the soil and prevent soil erosion. Large areas of fern cover are harvested annually to support many thousands of gem pits, and consequently, during the monsoon rains heavy erosion occurs in these areas.
2. Damage to plantations
When near-surface gem deposits are discovered in plantations of tea, rubber, coconut or pepper, mining is carried out without any consideration or respect for the trees. Valuable trees are either removed deliberately or fall down due to excavation. The loss of good plantations, damages the national economy.
3. Damage to rivers and river banks
Gem mining in rivers and streams is allowed by the NGJA only because of the uncontrollable nature of illicit mining. Illicit miners not only dredge the river bottom but also damage river banks by undercutting. Their operations may take place by day and by night. During dredging, fine clay particles can be released into suspension in the water and cause the death of river species; they can also prevent use of water for bathing and drinking. Furthermore, the sedimentation of waterways and dams reduces the efficiency of hydroelectric power plants.
4. Damage to buildings and properties
Tunneling under roads, buildings, canals, culverts and other structures can cause untold damage. There are many instances of land owners literally undermining their own properties, because it is sometimes worth the risk of forgoing a property in the hope of recovering high value gemstones.
Legislature
The State Gem Corporation Act No.13 of 1971 was repealed in 1993 and the National Gem and Jewellery Authority Act No.50 of 1993 came into effect with regard to the gem and jewellery industry. The Act states that:
‘No person shall carry on the gem industry except under the authority of a license issued by the Authority and every person who commits an offence under this Act shall on conviction after a trial before a magistrate, be liable to a fine not exceeding one million rupees or to imprisonment for a period not exceeding five years or to both such fine and imprisonment.’
The NGJA can, with the consent of the relevant parties, having regard to the circumstances in which any offence under this act was committed, compound such offence for a sum of not exceeding one third the maximum fine imposable.
The regulations in respect of the gem and jewelry industry were gazetted in 1972. Accordingly a license for mining for gems is issued under the following conditions:
1. The land owner/co-owners should give consent in writing to the prospective license.
2. If the land in question is cultivated; the consent of the cultivator too should be obtained if he is not the owner of the land.
3. In the case of cultivated land the consent of the regional office of the Agrarian Services Department should be obtained and the ASD takes a security deposit for each pit to ensure that the license restores the land after mining. The NGJA also takes a security deposit for each pit to ensure that the pits are closed, as is the responsibility of the NGJA to restore lands after mining. In the case of river dredging, substantial security deposits are required by the NGJA for the possible work involved in much larger than that for restoration of mining damage on high ground.
4. In mining cultivated land and rivers, water pumps are the only machinery allowed. Backhoes are permitted only in special circumstances and only with a very large security deposit since the excavations created are much larger than in normal pit mining.
Control of illicit gem mining
Raids are conducted with the assistance of the police to enforce the regulations and to apprehend offenders, because sometimes illicit gem miners attack unarmed field officers. There have been occasions in the past when even armed police have been the victims of illicit gem miners who sometimes flock in their thousands to new gem deposits discovered near the surface. The police have the authority to conduct their own raids and on such occasions, offenders are brought before a court of justice and due punishments is given.
Illicit mining in State lands, rivers and roads, or their reservations, is treated very seriously and the punishments are high compared with those for illicit mining on private land. Roads, rivers and their reservations, which comprise about 10 meters one each side of the road or river, belong to the government, and construction or excavation is not allowed in the reservations in order to safeguard these routes. If, for example, a water pump is seized on private land, it may be released with a fine of Rs.2500, whereas if the same pump were seized in one of the above mentioned locations, the fine may be a third of the value of the pump if it is a first offence, two thirds of the value if the offence is repeated and on a third offence the pump is forfeited to the State. Water pumps are the most common machines used in gem mining, and although gravel pumps, bulldozers and scrapers are rarely used, they too can be seized if used illicitly. This practice has been in operation for many years. However it has now been found that it is not a sufficient deterrent and therefore action has been taken to increase the severity of the punishment and to seize the machinery on the first offence. This is done particularly to discourage the use of gravel pumps in rivers and bulldozers and scrapers in large scale excavations in illicit mines.
Restoration of mined out lands
The security deposits kept at the NGJA are released only if the pits are closed and the lands are restored in a fit state for cultivation. Most often, when the value of gemstones found is very high, miners ignore the need to close pits and reclaim the land. The NGJA has established a rehabilitation fund with the money from those unclaimed deposits. During the recent past this fund has financed the following activities:
1. Conducting seminars for the gem mining community to educate them in environmentally friendly mining methods and restoration of lands.
2. Restoration of river banks by erecting brushwood dams along the original river boundary and filling the excavated area behind it; also planting suitable trees along the river banks.
3. Restoration of mined-out land by using bulldozers and scrapers and planting trees.
Conclusions
Mining by any method and for any mineral cause environmental damage and the only action that can be taken is to ensure that the damage is minimized. In the case of gem mining in Sri Lanka, many hundreds of thousands of people are engaged in gem mining, with or without a license from the NGJA. While the damage to the environment by legalized mining is minimal, the greatest harm comes from illicit mining and results in unfilled pits, soil heaps and pollution of waterways.
Illicit gem mining is not a problem specific to Sri Lanka, but faced by all gem producing countries. The discoveries of near surface deposits have caused gem rushes involving thousands of people in Sri Lanka, Madagascar, Tanzania, Brazil and in many other countries. Licensed mining can be supervised and strict rules can be enforced to reduce the environmental degradation. The field officers of the NGJA with the assistance of police make every effort to stop illicit mining, but the nature of such operations and the number of people involved prevents its complete eradication. The damage that illicit mining causes is offset to some extent by a rehabilitation fund established by the NGJA which is used to restore mined out lands.
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