The Gem Mining Industry In Sri Lanka

Sri Lanka has been famous from time immemorial for the great variety and abundance of gem minerals of extremely high quality and uniqueness, earned it the name Ratna Deepa meaning GemIsland. Nature in her bounty has chosen the bosom of Sri Lanka to enshrine some of  her rarest treasures.

 

Significant gem fields had been known from ancient times. Blue Sapphires, Cat’s Eyes, Alexandrites, Rubies, Star stones found embedded in layer of gravel and sand, in river beds, marshes, fields or accumulated at the foot of hills have made Sri Lanka the renowned island for gems. These precious stones perfected in the laboratory of nature lay hidden of countless ages, their luster undimmed, their value unrecognized.

Sri Lanka ranks with Myanmar, Brazil, South Africa and Thailand as one of the world’s most important gem bearing nations.  The story of Sri Lanka’s gems is as old as civilization itself.   Legends, myths and the occult have been associated with the long history of the island’s precious stones.   Gems are deeply embedded in the traditional beliefs and the religious life of the majority of  Sri Lankans.  Priceless gems are among the treasures kept in the relic chambers of  the great  Buddhist stupas in the island. 

The earth’s greatest concentration of gems in over 50 varieties is found within the country’s land area of approximately 25,000 square miles.   The Arabs called this the land Jazirat Kakut, which denotes the same meaning the Island of gems. The fame of her gems spread far and wide.  These priceless precious stones have adorned the crowns and thrones of royalty in many parts of the world

 Gem Mining Procedure

 Mining for gemstones is carried out on a cooperative basis. A number of miners form a group and share the costs of labour and profits from the sale of gemstones. This group is known as a Karuhavula. Its most important members are the investor and the miners. The investor finances the whole operation project up to the sorting stage. The miners decide on a suitable site, once a suitable site is chosen, miners excavate until they reach the gem bearing illama. A miner is able to judge the depth of the illama by inserting a steel rod into the earth until it reaches the layer below the illama, called the malava. Although the malava is found beneath the illama, there is a possibility of finding another layer of illama beneath the malava. The mine owner, being the head of a mine, is responsible for various legal activities and requirements. The organization and operation of a mine requires particular skills and some considerable experience of the industry. Mine owners tend to have been involved in gem mining for a significant period of time and the majority of them were middle aged.

Gem Mining Methods

There are 2 common mining methods. One is pitting: Pitting shafts are made to reach levels from 10 to 12 feet of pay gravel exist. Tunnels are made to collect the pay gravel around the base. Walls are structured with timber species that resist water rot and fern. Pits are generally confined to marshy terrain and paddy lands. Flooding is the main hazard in pit mining and the workers of the present day generally use water pumps to dewater.

The other is riverbed mining: Gems are also mined from riverbed material by using suction pumps for extraction of riverbed gravel for gems. Much harm can be done to riverbank stability by removal of gravel thus undermining the banks because there is no control of the operation.

Mining Methods Extraction

The mining methods used inSri Lanka are specifically developed and suited to the terrain. Compared to other gem producing countries some of the techniques are both simple and apparently obsolete. However, these methods are effective, adequately efficient and generally safe. Moreover the initial capital cost of mining operations is generally very low which permits greater involvement by relatively poor rural inhabitants. 

The Sri Lankan government has in fact banned the use of heavy, mechanized mining methods in gem mining. This not only prevents rapid, destructive depletion of an irreplaceable resource but also maintains an alternative source of revenue for much of the rural population who otherwise would be dependent almost entirely on agriculture.

                                                                                                         Deep Gem Pit view

Excavation of a pit is done usually by manual labour. In the first, stage, miners remove the non-gem bearing material, often soil, sand and gravel. This material is taken out of the pit and sorted and stored to be used later to fill in the hole. If the pit is shallow, the soil is removed with the miners standing at different levels of the pit and baskets being passed by hand to hand. If the pit is deep a pulley system is used. The illama is also removed in the same manner. In some instances the illama is excavated horizontally thereby creating a tunnel called a donava. These can extend from 6 to 9 metres form the shaft.

                                                                                                     

A temporary shed is made above the gem pit to protect the miners from the heat. Planks and logs are used to support the walls of the pit. While timber is usually used for this purpose, as prices increase for materials, some miners more use alternatives such as steel plates.  

Gempits sometimes suffer from accumulated water when the pit is dug and therefore mines are equipped with pumps to remove this water.

Time taken to mine is usually determined by the amount of illama found. Mining can range from a couple of days to a couple of years.

Washing Stage

Nambuwa

After being thoroughly washed, the contents of the basket, called the nambuva, is examined for gemstones. The basket is tilted at an angle allowing the sunlight to fall on the contents. The examiner usually determines if a stone is valuable by the colour, variation of colour, transparency form or shape. The same basket is examined many times by different people. This is the most important stage of the mining and done by the most experienced hands.

As time passed, new mining methods were discovered which did not hamper the cultivation of crops and the farmlands remained untouched. With advanced technology a vertical shaft was protruded until it reached the illiam. Feeder tunnels were built and were supported by timbers of wood and bamboo. The miners dug the tunnels and loaded their knapsacks with the precious gravel as made their way to the surface. Pumps operated full-time to keep the tunnels water free. The process of washing, screening and sorting took place on the surface, once the miner climbed up.

River Dredging

The gemstones erode from mineral rich rocks and eventually get washed down the rivers. Finding the right spot in the river is the tricky bit as strong currents sweep away even the heaviest gems and slow waters means sifting through a lot of unwanted debris.

Perhaps the simplest type of mine workings is the river dredging which are developed around the exploitation of present day stream gravels and illam exposed during down cutting and erosion by the river or stream. They also sometimes build dams to help them trap and sort the gemstones before they do the sieving. In their simplest form the dredging operation involves raking up a the river gravel or illam into a shallow pile using a long handled iron rake-like tool known locally as a ˜mammoty, and letting the river wash away the fines.  The resulting coarse fraction is then picked over by workers to extract the gem minerals. Often riffles, small dams and other barriers are built up on the riverbed to control the current and direct it into riverbanks or accumulations of gravel to assist in winnowing out the fine sediment and washing the gravels illegal dredging of riverbed gravels for gems.

 The gravel bar is an artificial construction and such features significantly modify the flow of the river resulting in damage to riverbanks and seriously affecting water supply. In some instances, particularly where the river is too deep to permit traditional dredging methods bottom sediment is dredged into weighted baskets pulled across the riverbed on ropes. The resulting basket of sediment is then processed on the riverbank.  River dredging is carried out both legally and illegally and if not closely controlled has significant negative environmental impact as well as health and safety implications for the workforce. River gravels are dug out using a hoe and washed in-situ. Unwanted material is simply discarded with fine-grained mud and silts held in suspension in the water.

Mine Workers

(Credit to fine water Gems for the Mining workers Pictures)

The majority of gem mining inSri Lankais carried out within communities by the local population.  It is pre-dominantly a low-technology labor intensive industry carried out as part of the communities a normal cycle of activities, usually when the agricultural workload is at a minimum and when the paddy fields are not producing crops. InSri Lankagem mining is solely a male occupation.

The numbers of staff employed by owners varied depending on the type of operation carried out with 5-6 people employed in shallow mines, 8-12 in deep mines and around 7 in river dredging. Total numbers employed tended to average between 11- 16 depending on the number of mines owned. The length of time of involvement in the industry also varied but the majority of owners had worked in the industry for at least 6 years with some having worked up to 30 years in the business. Most of them took up mining as it was shown to be profitable and several had progressed to become mine owners after working as gem miners themselves, using what they had earned to invest in their own mines. 

Gem mining is a physically demanding and labour intensive occupation and which is restricted to the male population inSri Lanka. Mine workers cover a wide range of ages from 18-50 with a relatively even distribution throughout this range. No children below the age of 18 are allowed to work in gem mining.

 Mine workers enter into a verbal agreement with a mine owner who is generally someone well known to the owner and local to the area. 70% of miners work in the industry because there is either no alternative employment or because they have specialist skills in the industry. Only a small proportion (20%) got involved with mining in anticipation of making high profits. Mineworkers tend to stay in the industry for several years with the greatest majority having worked in mining for 11-20 years. 

During any one year 80% of workers are employed for 7-10 months in mining, particularly in the more complex and labour intensive deep mines. Every mine has two leading mine workers nominated as foremen. They are generally experienced workers who possess a wide knowledge. It is their duty to allocate duties to the workers and advise them. Mine workers are paid a weekly allowance for their labour. Along with the weekly allowance miners are supported with meals at mines. No other form of payment is made because miners are entitled to a share of the profits from the mine. However, every mineworker expressed the view that the living allowance that they receive was not at all sufficient to cover their needs. Apart from the weekly allowance, a mineworker is entitled to about 3 % of the gem income from a mine. Since a mineworker is considered as a shareholder he is not supposed to work a specific number of hours as a waged earner. They tend to work at a stretch from morning till evening and at times they have to work late hours in order to complete certain work.   They also tend not to have holiday allowances because once a mine is opened the work has to be continued non-stop.  If a miner requires a period of absence due to illness or for any other reason he has to send another person to work on his behalf.

River miners are generally much poorer than the pit miners. The pickings are sparse. The work is long, tedious and gruelling and the miners have many mouths to feed. When they can’t find any gemstones, they pick fruit such as jackfruit from trees to survive on.

 

 

Customs and Astrological Background in Gem mining

Even today, astrology and offering to placate the gods are observed before commencing mining as it is evident that mining needs a lot of luck. Prior to beginning the mining, miners observe traditional customs by lighting an oil lamp placed inside a decoration or tender coconut leaves by the mine site.

An astrologer determines the time and date for commencement of work. Religious rituals include offerings made to the Bahiravaya who is the spirit or guardian in charge of the wealth hidden under the earth. Offerings are also made to the patron god of the region, for example, in Ratnapura, an area known for its abundance of gems; offerings would be made to the god Saman.

To be a gemstone miner inSri Lanka, a person must have the characteristics of a fortune seeker because mining is an arduous task where success is not guaranteed. Often miners work by the light of flickering candle metres below the earth. Miners may find a fortune in a piece of rough blue stone, hidden in the earth and obscured by mud, or may have to go hungry with no reward and fewer funds than they started out with.

 Sri Lanka Gem Mining History 

The secret of the sustenance of the gem mining industry for well over 2500 years rests on the unique traditional mining methods and the mining industry is one of the oldest cooperative work systems in the country.

According to geological history, gemstones were discovered in this charming island not prior to 500 B.C. During this period the Buddhists who traveled toSri LankafromNorthern Indiafound some precious gems while taking their bath in the streams and rivers of this island. The erosion of the rocks resulted to elongated placer deposits laden with precious gemstones in the beds of the flowing streams in the valleys which were located in the lower altitudes. The monks set these attractive colorful stones in their rings and other forms of jewellery like bracelets and armlets frequently worn during those days. During the course of their travels they traded these stones in the different markets ofAsiaandEurope. In this manner the gemstones reached new destinations in different parts of the globe.

References toSri Lanka’s precious stones are found in several historical records onSri Lanka.   Among them are Record of the Buddhist Countries (around A.D. 412) by the Chinese Buddhist monk Fa-hsien and The Historic Tragedy of theIslandofCeylon(A.D. 1685) by Portuguese Army Captain Joao Ribeiro.

Fa-hsien Writes: “…there is a district of about 10 square li which produces the mani jewel.  The king has posted guards here, and takes a levy of three tenths of the jewels that are found.’’

Describing Sri Lanka’s gems Capt. Ribeiro states: “…Here are all the valleys and mountains that are full of them and are obtained with little trouble; such as rubies, the finest that can be found anywhere within our discoveries, all in separate crystals; sapphires, topazes (some of them of extraordinary size) cat’s eyes… garnets, beryls, jacinths, tourmalines and various others, which are held in no account there, since they are the stones with which the river beds are furnished.’’

Marco Polo wrote of his visit in 1292: “I want you to understand that theislandofCeylonis, for its size, the finest island in the world, and from its streams comes rubies, sapphires, topazes, amethyst and garnet.” Little has changed since Marco Polo’s time except thatSri Lankafaces overpopulation and a faltering economy.

The island was known in the ancient world as Taprobane (copper colored in Greek). Native Veddahs, bathing in smooth flowing streams, noticed colored pebbles scattered in sandy bottoms. It was not until 500 B.C. that conquering Buddhists from northernIndiaalso discovered gems in the rivers and began to set rough stones into crude jewelry.

They bartered stones with traders from abroad and eventually the treasures found their way to the marketplaces ofAsiaandEurope. Ancient Greek and Chinese historians referred to the beautiful gems ofCeylon, and King Solomon reportedly wooed the Queen of Sheba with Ceylonese precious stones.

The origin of the term mani jewel is manikya or menik – the Sinhala and Sanskrit words for gems.   The district cited here is believed to be Ratnapura (city of gems) famed for precious stones throughout history.   The Ratnapura basin is considered the traditional area for gemstones. 

Basement Geology of Sri Lanka

Geologically about 90% of the Sri Lankan basement is composed of highly metamorphosed Precambrian rocks. These rocks vary in composition and metamorphic grade. Pegmatites, mafic dykes are other magmatic rocks are also found in the Sri Lankan basement. The north-western area and a small area of the south-western coastline have Miocene limestone. Small isolated sedimentary sandstone formations belonging to the Jurassic period are found at Andigama and Tabbowa. Red earth, Ratnapura bed, coral reefs, beach sand, beach rocks and alluvium can be considered as Quaternary deposits belonging to Pleistocene and recent epochs. Recent studies have subdivided these rocks inSri Lankainto three main lithotectonic units based on lithology and chronologic metamorphic history .

Sri Lankahas a unique combination of topography and climate, which has resulted in the formation of a valuable non-renewable natural resource in the form of gem and semi-precious stones.  The gem deposits ofSri Lankacontain a wide range of gem and semi-precious minerals some varieties of which are unique to the island and some that are particularly rare.  It is probable that many of the rarer, more valuable gem minerals are not recognized by the gem miners and are overlooked during sorting. 

The dominant gem mineral is corundum, in particularly the great variety of sapphires, rubies and geuda.  The majority of gem deposits are secondary alluvial gravels and contain a range of gem minerals with local and regional variations in relative abundance.

The Gem-bearing Areas

Approximately 25 percent of the island is estimated to be gem bearing. Nearly nine-tenths of the island is underlain by rocks of the Precambrian age, which is divided in to groups: The Highland South-western group, The Vijayan Complex and Wanni Complex.

Highland South Western Complex (HSWC)

Former Highland series and south-western group (Cooray 1962; 1984) has been included together and named asHighlandSouth-western Complex (HSWC). About 50% of the Precambrian basement ofSri Lankabelong to this unit. Deposition of supracrustal rocks took place at about 2000Ma years ago. The HSWC had undergone regional granulite grade metamorphism at 7500-9000 C temperatures and 8.5-7.5 K.bar pressures. This event took place at about 650-550 Ma years ago (Kroner et. al. 1991). The HSWC is composed of meta-sedimentary rocks such as quartzite, marbles, calc-silicates and garnet sillimanite-gneisses, meta-volcanic suits, mafic to granitic granitoid intrusives and mafic dykes.

Vijayan Complex

The vijayan complex is exposed in eastern and southernSri Lanka. The depositional age of supracrustal rocks of Vijayan complex is around 1100Ma. It has been subjected to amphibolite grade metamorphism around 456-591Ma. The vijayan basement is composed mainly of granitoid gneisses (Tonalite to Leucogranite) and migmatites. Metasedimentary rocks are found in minor amounts as xenoliths. In contrast to Wanni complex horndblend bearing calc-alkaline plutonic rocks are common in this unit (Kroner et. al. 1991).

Wanni Complex

The former West Vijayan Complex (Cooray 1962; 1984) has been re named as the Wanni complex by Kroner et. al.. (1991). The wanni complex also has been subjected to the same Granulite grade metamorphism of HSWC. However its supracrustal rock deposition was simultaneous to the Vijayan complex (1100 Ma). Paleo-metamorphic pressures of the Vijayan complex are lower than that of HSWC.

The Kadugannawa Complex (KC) is situated within the HSWC, aroundKandyand Peradeniya. This complex has zircon dates (660Ma-550Ma) and Nd model ages (1100ma) comparable to the Wanni complex (Kroner et. al., 1991).

Parts of the Kadugannawa complex have experienced granulite grade metamorphism (Schenk et. al., 1991). Evidence for a retrogressive event has also been preserved at some locations.  The KC is composed of hornblende – biotite and quartzo – feldspathic gneisses, minor amphibolites and anorthosite and supracrustal rocks.  There is no evidence to show that the KC is a nappe structure of the Wanni complex. Therefore it is recognized as a differentiated suite of calc-alkaline intrusive rocks intruded into rocks of the HSWC around 890-1000Ma ago.  Most gem-bearing areas ofSri Lankaare underlain by the granulite grade metamorphosed Highland Complex.  Some gem occurrences, such as in the Okkampitiya gem fields, are found outside the Highland Complex.  However it is thought that the gems originated in the Highland Complex and were later transported by rivers and deposited in this area.

Most gemstone minerals are found in theHighlandgroup, which is the oldest rock formation .A broad belt that cuts across the centre of this pear shaped island. This belt has its edges in the shape of a trough and is bordered by mountain peaks. The trough which has components of crystalline metamorphosed rock along with schist, marble, pegmatite and quartzite deposits erodes and results in the formation of gemstones along the beds of rivers and streams in the valleys through which they flow.

The gem-bearing belt is approximately 80 miles in length and 20 miles in width and lies south-west of the central hills, as well as other pockets of gem producing areas.

The areas of Ratnapura, Pelmadulla, Balangoda, Eheliyagoda, Kalawana and Nivitigala in theSabaragamuwaProvinceconsist of densely concentrated deposits of gem materials as compared to most of the other deposits in the country. The most noteworthy gem bearing deposits next to Ratnapura and other areas in theSabargamuwaProvinceare located in and around Elehera in Polonnaruwa District in theNorthCentralProvince. In addition to the aforementioned gem fields there are a number of other notable gem deposits located in Okkampitiya, Kataragama, Matale, Meetiyagoda, Kolonne, Yakkalamulla and Buttala areas.