In the first stage of the excavation, miners remove the non-gem-bearing material which includes soil, sand and gravel. Thismaterial is transported to the surface and stored. It will be used later to fill in the pit, not only for environmental reasons, but also to pfevent a creation of favourable breeding grounds for the malaria mosquitoes as well as to prevent animals or people injuring themselves by falling into the old, disused mining pits.
The process of removing and collecting the soil, sand and gravel is done in two ways. If the pit is shallow, the miners stand at different heights in the pit. The soil and other material is passed from hand to hand and is deposited beside the pit. Illama is also collected in a similar manner. On the other hand, if the pit id fairly deep, removal of material is done by means of a pulley with a basket tied to the end of a rope. In some instances, illama is also excavated horizontally, thereby creating a tunnel known as donava. Donava may extend from 6 to 9 metres, or occasionally even mone, away from the shaft.
The period of the excavation work primarily depends on the depth at which illama is found. This varies from one locality to another. The amount of illama determines the time taken for the entire work. This may be completed in a minimum of 3 to 4 days, but there are instances when the operation has been completed within a year or two.
After a sufficient amount of illama has been collected at the surface, miners come up to the surface for the washing and sorting process. This is the most important part of the mining operation.
WASHING OPERATION
Washing is often done at small reservoir built close to the gem pit with water pumped out from the mine. In places where the pit is situated in close proximity to a river, no reservoir is required.
First moners put a few handfuls of illama in a shallow circular wicker basket. This is then immersed in water and turned a number of times to remove any mud, gravel and sand. Illama is generally grey and mottled in shades of brown. A coating of clay covers all pebbles making gem minerals indistingushable from all the other stones.
Once illama is thoroughly washed, the residue left containing heavier pebbles, may also include gem minerals. The most abundant constituent of the gem bearing gravel or illama is quartz,but one may also find some rare-earth minerals, such as thorite, and thorianite,etc.
SORTING PROCESS
When a basket of illama has been thoroughly waashed, the contents, called nambuva, are examined for gem minerals. The basket containing gem, non-gem quality and other pebbled is tilted at a slight angle allowing the transparency, form or shape etc., help the examiner to determine the quality and variety of a stone. The same basket is inspected anumber of times by several different persons.
Although miners may not have any knowledge of gemmology, they are certainly confident and capable enough to identify the variety and quality of most gem minerals. Their main task is to look for precious stones such as sapphires, rubies and alexandrites, etc.which can often be identified to at a first glance. However, a comparatively tiny but a good quality precious stone may realize a much higher price than a large gem quality semi-precious stone. Therefore, the sorting stage is considered to be very important. This work is generally done by the most experienced and skilled people involved in the operation.
RIVER WORKINGS
Although gem minerals are generally obtained from pits, they are sometimes obtained from rivers. In river workings miners use about 10 metre long handled mammoties to stir up and collect sediments of the river bed. This work is done after the rainy season is over
Miners build dams in shallow rivers where the water flow is slow. In this method of gem mining, miners stand in the river facing the direction of the water flow. They hold their mammoties on the river bed collect sediments including gem minerals.
This kind of searching has a number of advantages. It can be done without investing large sums of money, also gem minerals may be obtained after a few hours of work. River workings are commonly carried out in the areas of Rutnapura, Pelmadulla and Balangoda. Some of the best known stream where gem gravels have been expoited on a large scale Ganga between Ratnapura and Pelmadulla, and Wey Ganga between Ratnapura and Kahawatta.
AREAS OF GEM MINING
The city gems of Shri lanka, Ratnapura(ratna-gems; pura-city), is located 100 kilometres 963 miles) from Colombo. The gem industry in this city began in very early times. The other gem producing areas in the country are Avissawella, Balangoda, Eheliyagoda, Elahera,Horana, Kandy, Kataragama, Matale, Nivithigala, Nuwara Eliya, Okkampitiya, Pemadulla and Polonnaruwa. Meetiyagoda, aminor village located to the south the island, is known for its moonstones.
In some gem mining areas almost all gem varieties are found, while in other sites only a few varieties are known to occur. The conclusion of a recent survey on the occurrence of different types of gem minerals in the major gem mining areas is remarkably improved over the past few years.
AVISSAWELLA mostly all varieties of corundum mineral including geuda
BALANGODA blue sapphire, yellow sapphire, white sapphire,ruby,geuda, alexandrite, spinel, topaz
EHELIYAGODA blue sapphire,yellow sapphire, ruby and geuda
ELAHERA mainly pyrope garnet, but also other varieties including sinhalite
HORANA rare stones, chrysoberyl cat's, alexandrite and geuda
KATARAGAMA hessonite and pyrope garnets, sapphire and geuda
MATALE(in Rattota) topaz
MEETIYAGODA moonstone
NIVITHIGALA geuda and most other gem varieties
OKKAMPITIYA blue saphire,yellow sapphire and geuda
POLONNARAUWA garnets,star sapphire,mainly blue sapphire, star ruby and some rare stones
RATNAPURA almost all gem varieties