Gemstone and Diamond Mining Through the Years
Gemstones have been a symbol of wealth from the ancient times up to the present. These stones with their own characteristic, unique and special properties have always been associated to beauty too. Popular and famous persons throughout history, especially those from the noble family have used gemstone to adorn not only themselves but their dwellings as well.
In the United States, mining of these stones has been for recreational activity only for collectors and hobbyists since 1935 (Gemstones Production, USGS). Nevertheless, as the value of gemstones inflated, large scale mining operations have been initiated. In this paper, we would explore the world of gemstones; what truly fits the word gemstone, how are they classified and the methods of mining.
The word “gem” actually came from the Latin word gemma, which means “bud” (Microsoft Encarta). It is a very fitting name since gems seem to bud out of the earth’s crust like flowers in a garden. Gem or gemstone means any mineral or organic material that can be used to decorate one’s body, for display or can be considered an object of art due to its unique properties it possesses such as beauty, rarity and durability. Colored and diamond gemstones are subcategories of gemstones. Basically, colored gemstones are all other stones except diamond such as amber, coral and shell (Olson 32.1).
On the other hand, natural gemstones are minerals, stones or any organic matter that can be cut, polished, or treated for use as jewelry or other personal ornament (Gemstones Terms, USGS). Gemstones can be further classified as precious or semiprecious gemstones. Precious gemstones have beauty, durability and rarity, while semiprecious gemstones have only one to two of these characteristics (Gemstones Terms, USGS). Diamond, ruby, sapphire, emerald, aquamarine, topaz and opal are classified as precious gemstones while others are treated as semiprecious (Gemstones Terms, USGS). Since gemstones are rare, they are not plentiful and these stones do not form ores like other mining products. They tend to be scattered throughout a large body of rock or can be crystals found on small cavities of rocks (Gemstones Environment, USGS).
Gemstones are primarily found from Tennessee, Alabama, Arkansas, North Carolina, Oregon and Arizona (Gemstones Specialist 64). However, most gem diamond reserves are not found in the United States. Diamonds are usually mined from Southern Africa, Russia, and Western Australia (Gemstones Specialist 65). The very first used as jewelry were amber, amethyst, coral, diamond, emerald, garnet, jade, lapis lazuli, pearl, rock crystal, ruby, serpentine and turquoise (Olson 32.1).
In the US, the commercial gemstone industry consists of individuals and companies that mine gemstones or harvest shell and pearls, firms that manufacture synthetic gemstones and individuals and companies that cut natural and synthetic gemstones (Olson 32.1). Worldwide, the industry is only composed of two sectors: diamond mining and marketing and the production and sale of colored gemstones (Olson 32.3).
Throughout the year, few of the diamonds mined are of gem quality; much of them are of near-gem and industrial in quality. Gem quality diamonds display high standards of excellence in quality and can be sold as jewelry. Clarity of such diamonds is from flawless through to visible inclusions. On the other hand, near-gem quality represents diamonds that fall between gem and industrial quality and thus can be used for either purpose. Clarity of this set is from visible inclusions to industrial. Lastly, industrial quality diamonds are of low quality and cannot be used as jewelry or adornment. These diamonds are suitable only for industrial use such as dentist’s drills and earthmoving equipment (Mining Diamonds).
Diamonds are formed beneath the earth’s surface and required tremendous pressure and temperature. Like diamonds, most gems are crystals formed by cooling hot gases, solutions, and melts. As the earth’s soil surface weathers and erodes, and rivers forcefully flow through, gemstones may be exposed and be unearthed where one can even simply bend over the riverbank and pick them up (Microsoft Encarta).
One of the two primary industries of early civilization is mining. Like agriculture, it is one of humankind’s earliest endeavors (Introduction to Mining 1). In 3400, Egyptians in Sinai did the first ever-recorded mining where they have found turquoise (Introduction to Mining 7). Usually, gemstones are excavated at the surface. However, through the years, underground mining especially for diamonds have been developed. Unlike surface mining, underground mining is more complicated and expensive. It involves the efficiency, safety and permanence underground (Introduction to Mining 11).
Mining is the process of obtaining useful minerals from the earth’s crust. Its process requires excavations in underground mines and surface excavations in open pit or open cut mines. Thus, it involves physical removal of rock and earth to acquire gems and other important minerals. (Microsoft Encarta). Mining consists of four stages. These stages are prospecting or search for mineral deposits, exploration or the work included in evaluating the extent of economic value of the deposit, innovation or the work of preparing access to the deposit so that the minerals can be extorted from it and exploitation which is the process of extracting the minerals (Microsoft Encarta).
Methods of Mining
There are several methods of mining. For gemstones, they are usually obtained on rivers and shores. However, there are also other ways of obtaining them in large scale mining operations. Exploitation methods can be classified into two categories based on setting which are surface and underground mining. Surface mining operations consists of mechanical excavation techniques such as open pit and open cast or strip mining. There are also aqueous methods such as placer mining and solution mining. On the other hand, underground mining is usually categorized into unsupported, supported and caving methods (Introduction to Mining 11).
Placer mining involves excavating loose or alluvial such as sand and gravel. The sought after gems are separated from the sand or gravel by a series of screens, jigs and sluices. This type of mining is usually used for diamonds and rubies (Microsoft Encarta). At present, surface mining involves production of blastholes 3-15 inches in diameter by rotary or percussion drills for the placement of explosives in order to remove consolidated rock. The explosives are then inserted and detonated. The material then is loaded and hauled for transport (Introduction to Mining 15).
Diamonds are mined by pipe or alluvial methods. In pipe mining, extraction of diamonds is done from volcanic pipes. Unlike other gems, diamonds are usually found underground and on volcanic rocks and lands. In diamond pipe mining, large areas are exploited wherein an average of 250 tons of volcanic rock is mined just to produce a one-carat gem quality polished diamond (Mining Diamonds). Due to this intricate and costly process, diamonds are really rare and precious. Diamond pipe mines are composed of kimberlite material called blue ground. At the start, kimberlite is dug from the surface by rough opencast mining. Nevertheless, as the surface deposits are exhausted, pipe mining is employed by sinking shafts into the ground at the edge of pipes and tunnels are driven into the deeper parts of the pipes. By doing so, diamond-bearing rock is excavated and is then transported for screening (Mining Diamonds).
Another method of diamond mining is alluvial mining. In this method, diamonds are extracted from riverbeds or ocean beaches. It is true that diamonds are made inside volcanic pipes and lands, however, millions of years allowed that some of the diamonds formed are weathered out of the volcanic pipes and carried to great distances by rivers and oceans. Thus, the process of alluvial mining involves building a wall that holds back the surf. About 25 meters of sand is demolished aside to reach the diamond-containing level in the ocean and riverbeds. The diamond-containing sand is then acquired and transported to screening plants (Mining Diamonds).
In screening plants, diamonds with kimberlite are cleaned and purified. Separation of the diamonds from the kimberlite ore involves a process much like the panning of gold. The kimberlite ore is put into large funnels along with a heavy fluid and is then, mixed in a rotating manner. Since diamonds are heavier than the other materials from which it is mined, they sink into the bottom of the funnels and spill out. After this process, the diamond is almost free from other waste (Mining for Diamonds).
Diamonds can then be washed on shaking grease-covered tables. Uncut diamonds then adhere to the grease while the other fragments of waste ore are vibrated past and are discharged to tailings pile. The tables are then scraped for diamonds in the grease and then are boiled to melt the grease and separate the diamonds (Microsoft Encarta). Finally, these diamonds are separated into different grades or quality as industrial, gemstone or near-gem grades.
Rough uncut diamonds do not actually look attractive. Such diamonds are needed to be cut and polished before anyone can see their beauty and relevance in personal adornment and jewelry. The process of cutting and polishing originated in India where Indian natives discovered a way to make rough diamonds glisten by simply grinding another diamond against it (Mining Diamonds). Diamonds are known for their hardness, no material has ever been found which is capable of cutting diamond until the Indians found out that diamonds could actually be cut and polished by diamonds. The process of cutting and polishing typically lasts for several hours to several months. After which, the diamond will turn out lighter for at least half of its original weight (Mining Diamonds).
Diamonds are first carefully examined before cutting. Diamonds are popularly cut into round brilliant since this shape gives the greatest possible brilliance with the minimal weight loss. Cutting uses an instrument similar to grinders. This cutting instrument is made of a paper-thin metal disc coated with diamond dust revolving at a fast speed. Lasers can also cut diamonds nowadays. The corners of the diamonds are then rounded by grinding another diamond producing some dust that can later be used in polishing. Diamonds are then polished to make them sparkle brighter. The diamond dust from the cutting is placed on a turntable made of iron and oiled. The cut diamond is then grinded against the turntable until it sparkles beautifully (Mining Diamonds).
Gemstones are treasures not only of powerful people but also of mighty and ancient civilizations. As humankind became civilized, gemstones such as diamonds and sapphires became symbols of prosperity and elegance. Their crystalline structure, the rarity, and the arduous process of mining them have lived up to their symbolism throughout the years and continue to do so.
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