Gemstone Mining Methods

by Sheweta Dhanuka

Gemstones are treasured by most of us and to retrieve these precious gems from deep down the earth crust one has to go in for treasure hunt. Gemstone Mining is very complex and tedious process that requires huge input of valuable resources such as time, workforce, equipments and knowledge etc. There are different methods for recovering the gemstone from the lap of Mother Nature. The appropriate procedure is selected depending upon the circumstances but no matter what method is selected the entire process of gemstone mining needs to be very systematic as it costs a lot of money. The total process of gemstone mining is so intricate that inspite of putting in so much efforts there is no surety of the results. Failures and disappointments always have higher percentage than the success.

In order to attain the positive results, the first and foremost requirement of this exclusive process is to identify the gemstone deposits. This necessitates the vast knowledge of gemstone properties, with the help of this key the deposits are identified where there could be the probability of the finding the precious and semi precious gems. The route of gemstone mining is executed all the way through highly developed and technical system. But we all know, traditional methods have there own uniqueness that cannot be denied even after developing new scientific methods. All the methods are categorized into two types of mining viz. surface mining and underground mining. First always the surface mining is done and then when fruitful results are not achieved underground mining is brought into action. Underground mining is always more expensive because -

Surface Mining

Surface Mining is done to obtain gemstones from the rocks near to the surface of the land. There are six different types in which surface mining could be done. The miner decides on surface mining technique depending up the overall cost and time. These methods are:

[1] Hydraulic Mining

In this method powerful jets of water is used to loosen the gem material from the overburden. The miners make channels on the rock/gravel hillsides in form of sluices where water under pressure is sprayed. The water pressure splits down the rock and washes large rock piece of it downhill. And finally the gems as raw stones are separated. This mining is very harmful for the environment as it wrecks the mountains and blocks the rivers. Hydraulic surface mining was found way back in 1800s and continued till 1960s but now it is stopped completely due to its disastrous consequences to the natural beauty.

Hydraulic mining

Hydraulic mining

[2] River Panning

River Panning is the method where gemstones are collected while washing the gravels from a river/stream in the mining area. It is also known as placer mining. This method is initiated with the identification of the gravel which may contain gems. The best place to find the gravel deposits is in obvious gemstone producing rivers, streams and creeks. Then a large pan is filled with water and shaking it back and forth to settle the heavy material to the bottom of the pan. The lighter material is washed over the top of the pan and larger rocks & pebbles are removed by scooping them over the edge. These steps are repeated until there is only about a tablespoon or two of concentrates left in the pan. Nearly all panning is completed using the riffles in the pan.

The left over concentrated is then shifted to a smaller clean pan. Drop of liquid soap is added to keep the tiny chips from "floating." The less weighty material shall float down with the water and the gems, in case the gems are there, it shall stick and stay at the upper end of the pan. This is a very time consuming method and the chances of success are very less.

River Panning of Gold

River Panning, image: Science Photo Library

[3] Open Pit Mining

This mining can only be accomplished under the guidance of an experienced Gemologist. First he scrutinizes the location to be mined with respect to value of the rock and minerals below the surface, cost of digging the mine and the after effects of mining on the environment. The monetary value of rocks and minerals keeps appreciating over the years so once it is profitable to mine then only open pit mining is done.

Once the location is finalized, layers of the land are removed one after the other till rocks are visible. Then the rocks are removed and gems are searched for in the rocks and sent for further processing. Sometimes explosives like dynamite are used to reach deeper and deeper to recover the required rock possessing the gems. After the mining is done, the area turns into pit which is used as landfill. Landfill is huge open space used for dumping the garbage. Once it is fill it is covered the layer of mud. Finally when the trash decomposes in long run and land can be again used for some other purpose apart from mining. This mining method is relatively easy and cost effective. However, it is performed only when rocks are near to the surface of the land.

Open Pit ekati diamond mine

Open pit Ekati diamond mine

[4] Strip Mining

This process is very similar to open pit mining. The mining site is identified; the trees and bushes are removed with the help of the bulldozer. The remains are dumped at the nearby area. Many small-small holes are drilled distant from one another through the rock. Dynamite are placed inside these holes and blasted to get the rocks with gemstones. Raw stones then are sent for further processing. This mining is done in long strips so it is called as strip mining. Once the first strip is completed, the second strip starts. The dirt obtained in making the second strip is dumped in the first strip. Similarly it goes on till the entire site is worked on. And in the last strip the remains of the first strip is filled in. The top layer is of mud that is leveled on all the strips together making the land ready of re-use.

[5] Mountaintop Removal Mining

In this mining method, the mountain top at the ground level is cleaned by cutting the trees and shrubs. Then using the dynamite the top of the mountain is blasted for making the vein. This gives huge blocks of rocks from which the gemstone in unprocessed form are retrieved. The dirt obtained after the blast is dumped into the valleys with the help of bull dozers and trucks.

[6] Quarrying

This mining method is quite less hazardous to the environment. The rock attained from this mining is used for making buildings. Therefore, the way quarrying is to be done depends upon the purpose of re-use of rock. The rocks are drilled to use the left over for cement, it is blasted with dynamite to use the rocks for the interiors of the house like flooring, kitchen slabs. In any of the method after getting the rock the gemstones are searched and then the rocks are spared for re-use.

Underground Mining

Underground mining is done when surface mining is not possible or does not yield rewarding results. Moreover, precious gemstones are mostly found through underground mining. In the method the miners make underground rooms where they further dig the ground more and deeper. Underground mining is done in numerous ways. These are -

[1] Borehole Mining

As the name suggests holes are drilled very deep inside the plain land. In these holes a long huge tube (having enough space to allow the water to pass through) is dropped. Then water is pushed down the tubes with the force, the water hits the rock and breaks it down. The water combines with the rocks, dirt and mud to make slurry. This mixture is pumped back from the tubes and stored into tanks. The unwanted water is thrown out the left over rocks are processed for gems. This method is very much environment friendly and the shifting from one place to another is quite easy.

[2] Drift Mining

This mining is done on the mountain sides. Rock are identified which are on the sides of the mountain. The opening is made below the identified rock. These opening are made horizontally and are known as tunnels/drifts. From the drifts the desired materials are retrieved as due to gravity the material comes down the hill easily. This is one of the cheapest gemstone mining methods and gives good results as well.

[3] Shaft Mining

In this method, vertical tunnels are created below the mountains and through the lift miners moves up and down the mines. The vertical tunnels are called as shafts. Two shafts are created. One is used for the movement of the miners inside the shafts and the other shaft for brining the material on the ground. From the man shaft, small tunnels are made that reaches the rocks possessing the gems. These small tunnels are used for blasting and when the rocks breaks into small chunks those are brought up on the ground through the second shaft. After the work is finished the mines are closed by refilling the shafts with dirt, mud, pebbles and cement etc. This is quite a costly method.

[4] Slope Mining

Slope mining too has shafts but these shafts are first made slant and then parallel to the ground. Usually, this mining is done when it is not possible to make the straight shafts therefore it is named as slope mining. The tunnels are not very deep in the gemstone mining method. Using the conveyor the broken are rocks are brought out.

[5] Hard Rock Mining

Same as drift mining, tunnels are made inside the grounds instead of mountains. First a small opening is made which is referred as Adit. Later, using Adit, tunnels are made vertically deep down the ground using explosives like dynamite. The tunnels are called as shafts. Like wise many shafts are made and each one has a different function. For examples - one could be used for miners going inside and coming back to the ground, second for air ventilation and so on. At the end of the shaft, there one more shaft is made that leads to the rock that contains gemstones. Deep inside the earth crust many different floors are created and one floor after the other is completed. This is the most dangerous gemstone mining method and therefore is brought into practice quite less.

Hard Rock mining of Tanzanite

Hard Rock Tanzanite Mining

In all the mining methods the rocks are broken into medium or small chunks using the explosives such as dynamite. The broken rocks are then sent to the other processing plant where the gemstones are obtained in the form of raw stone. These raw stone reach to the next level of gemstone processing that involves cleaning, cutting and polishing etc. The gemstone that finally gets mounted to the awesome jewelry pieces, from the scratch passes through the numerous steps that involve the sweat of many people.

It is very easy and classy to wear the gemstone jewelry but the amount of hard work involved in obtaining these precious and semi-precious gemstones through the mining methods is immense. Gemstone mining methods are certainly mind-numbing and it is an exclusive proficiency of finding inimitable raw stones from mines that are crafted into amazing gemstone jewelry!!

 
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