The Williamson diamond mine (also known as the Mwadui mine) is a famous diamond mine in Tanzania; it became well known as the first significant diamond mine outside of South Africa. The mine was established in 1940 by Dr. John Williamson, a Canadian geologist, and has been continuous operation since then, making it one of the oldest continuously operating diamond mines in the world. Over its lifetime it has produced over 19 million carats (3,800 kg) of diamonds. The Williamson mine, once owned by its namesake Dr. Williamson and later nationalized by the government of Tanzania, is now majority owned by the South African diamond giant De Beers (75 percent ownership), with the government of Tanzania owning the remaining 25 percent. There are a limited number of commercially viable diamond mines currently operating in the world. ... A scattering of round-brilliant cut diamonds shows off the many reflecting facets. ... The El Chino Mine located near Silver City, New Mexico is an open-pit copper mine Mining is the extraction of valuable minerals or other geological materials from the earth, usually (but not always) from an ore body, vein, or (coal) seam. ... The United Republic of (Jamhuri ya Muungano wa Tanzania in Swahili) is a country on the east coast of central Africa. ... The Republic of South Africa is a large republic located at the southern tip of the continent. ... 1940 was a leap year starting on Monday (link will take you to calendar). ... Dr. John Thornburn Williamson (1907-1958) was a Canadian geologist famous for establishing the Williamson diamond mine in present-day Tanzania. ... Canada is a sovereign state in northern North America, the northern-most country in the world, and the second largest in total area. ... A geologist is a contributor to the science of geology. ... The carat is a unit of mass used for gems, and equals 200 milligrams. ... Nationalization is the act of taking assets into state ownership. ... The De Beers Group is a London and Johannesburg based diamond mining and trading corporation. ...

Description

The Williamson diamond mine is a large open pit mine currently about 90 meters (300 ft) deep. Diamond mining operations at the Williamson diamond mine are composed of four distinct activities: mining of the pit, re-treatment of tailings to recover missed diamonds, and gravel mining both on the property and adjacent to the property where gravel has been alluvially deposited. The open pit mining and tailings re-treatment are the largest of the four operations. The mine currently employs about 1,100 staff, mostly Tanzanians. Tailings are the rejected material from mining and screening operations. ... Gravel Gravel is rock that is of a certain size range. ... Alluvium is soil land deposited by a river or other running water. ...

Location

The mine is located about 160 kilometers (100 miles) south of the town of Mwanza on the shores of Lake Victoria in Tanzania, in the Shinyanga region. Dr. Williamson, the discoverer of the site, first owner and namesake of the mine, named the site "Mwadui" after a local chief; "Williamson" and "Mwadui" are now virtually synonymous in the diamond mining world. Mwanza is a city in northwest Tanzania and a southern port of Lake Victoria. ... Lake Victoria or Victoria Nyanza is one of the Great Lakes of Africa. ...

Geology

The most important geological feature of the Williamson diamond mine is the kimberlite pipe on which it is located. At 146 hectares in area at surface level, it ranks as the largest economically exploitable diamond-bearing volcanic pipe in the world. Recent exploratory drill cores conducted by De Beers have indicated that the pipe is a pyroclastic kimberlite, not a hypabyssal kimberlite as earlier suspected. This indicates that it may be possible to extend the current 90-meter deep open pit to as much as 350 meters deep, and continue down even further with underground mining operations. However, a review of mine operations and long term plans continues, and any discussion of deep expansion of the open pit is speculative in nature. Hewn kimberlite core sample from the James Bay Lowlands region of Northern Ontario, Canada. ... Volcanic pipes are subterranean geological structures formed by the violent, supersonic eruption of deep-origin volcanoes. ... A hectare (symbol ha) is a metric unit of surface area, equal to 100 ares (the name is a contraction of the SI prefix hecto + are). ... Pyroclastic rocks are formed from lavas which are ejected into the air, as occur in pyroclastic flows or Plinian eruptions. ...

Production

The Williamson diamond mine is now characterized by low ore grade of about 6 carats per hundred tons (12 mg/t) of ore. This is a dramatic decrease from its production in the mine's early life; during the first 25 years of operation, average ore grade was bout 30 carats per hundred tons (60 mg/t); in the first few years of full operation grades were as high as 62 carats per hundred tons (124 mg/t), or 10 times the ore grade realized today. Production in the 1950s and 1960s was usually between 500,000 and 750,000 carats (100 and 150 kg) per year; the peak year of production was 1966, when 924,984 carats (185 kg) were produced. Today production levels for all Williamson mine diamond recovery activities is about 300,000 carats (60 kg) per year. The carat is a unit of mass used for gems, and equals 200 milligrams. ... An ore is a mineral deposit containing a metal or other valuable resource in economically viable concentrations. ... Events and trends Technology United States tests the first fusion bomb. ... Centuries: 19th century - 20th century - 21st century Decades: 1900s 1910s 1920s 1930s 1940s 1950s - 1960s - 1970s 1980s 1990s 2000s 2010s Years: 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 Events and trends The 1960s was a turbulent decade of change around the world. ... -1...

Notable stones produced at the Williamson mine include 54 carat (10.8 g) flawless pink diamond (presented to then-Princess Elizabeth and Prince Philip upon their wedding in 1947), and a 388 carat (77.6 g) diamond found in 1990. Diamond clarity is a quality of diamonds relating to the existence and visual appearance of internal defects of a diamond called inclusions, and surface defects called blemishes. ... Jewelers set diamonds in groups of similar colors. ... Her Majesty Queen Elizabeth II (Elizabeth Alexandra Mary) (born 21 April 1926), styled HM The Queen, is the Queen regnant and Head of State of the United Kingdom, as well as the Queen of Antigua and Barbuda, Australia, The Bahamas, Barbados, Belize, Canada, Grenada, Jamaica, New Zealand, Papua New Guinea... HRH The Duke of Edinburgh His Royal Highness The Prince Philip, Duke of Edinburgh (Philip Mountbatten), styled HRH The Duke of Edinburgh (born June 10, 1921), is the consort of Queen Elizabeth II of the United Kingdom of Great Britain and Northern Ireland. ... 1947 was a common year starting on Wednesday (link will take you to calendar). ... 1990 is a common year starting on Monday of the Gregorian calendar. ...

History

The diamond industry of Tanzania in the 1930s was characterized by a scattering of very small mining operations that were insignificant in the economic makeup of the country. Dr. Williamson was hired by one of these operations, the Mabuki diamond mine, in 1938 and used it as his base for diamond prospecting in the region. In 1940 he discovered the Mwadui kimberlite pipe; over the next several years he developed the mine, although he was hindered by difficulty in procuring equipment and raising funds due to World War II. By the 1950s he had developed the Williamson diamond mine into the first significant diamond mine in Tanzania, with state of the art equipment and a labor force of several thousand. The mine was noted for numerous technical innovations in diamond mining which were developed under Williamson's watch. Williamson closely managed the mine until his death in 1958 at the age of 50. Events and trends Technology Jet engine invented Science Nuclear fission discovered by Otto Hahn, Lise Meitner and Fritz Strassmann Pluto, the ninth planet from the Sun, is discovered by Clyde Tombaugh British biologist Arthur Tansley coins term ecosystem War, peace and politics Socialists proclaim The death of Capitalism Rise to... 1938 was a common year starting on Saturday (link will take you to calendar). ... Prospecting is the act of searching for minerals or ore deposits. ... 1940 was a leap year starting on Monday (link will take you to calendar). ... Mushroom cloud from the nuclear explosion over Nagasaki rising 18 km into the air. ... Events and trends Technology United States tests the first fusion bomb. ... 1958 was a common year starting on Wednesday (link will take you to calendar). ...

Williamson's heirs sold the mine for about £4 million GBP to an equal partnership between De Beers and the colonial government of Tanganyika on August 13, 1958. In 1971, upon Tanzania's independence, the government nationalized the mine. Although details are unknown, De Beers and other diamond industry players speculate that mine performance deteriorated significantly in the 1980s under government management. Suspected causes of this are a decrease in ore grade as the mine's richer deposits were worked out, loss of skilled foreign management and engineering staff, a bloated labor force resulting from government employment efforts, and inadequate capital investment in the mine's equipment. Perhaps as a result of this poor performance, Tanzania invited De Beers to purchase back into the mine, which the company decided to do. In 1994 De Beers bought 75% of the Williamson mine, with Tanzania retaining the remaining shares. The pound sterling, which strictly speaking refers to basic currency unit of sterling, now the pound, can generally refer to the currency of the United Kingdom (UK). ... The De Beers Group is a London and Johannesburg based diamond mining and trading corporation. ... In politics and in history, a colony is a territory under the immediate political control of a geographically-distinct state (or city, in ancient times). ... Tanganyika was an East African republic within the British Commonwealth, named after Lake Tanganyika, which formed its western border. ... August 13 is the 225th day of the year in the Gregorian Calendar (226th in leap years), with 140 days remaining. ... 1958 was a common year starting on Wednesday (link will take you to calendar). ... 1971 is a common year starting on Friday (click for link to calendar). ... Events and trends The 1980s marked an abrupt shift towards more conservative lifestyles after the momentous cultural revolutions which took place in the 1960s and 1970s and the definition of the AIDS virus in 1981. ... 1994 was a common year starting on Saturday of the Gregorian calendar, and was designated the International year of the Family. ...

Since 1994, De Beers has acted to improve the performance of the Williamson diamond mine by trimming work force, making needed capital investments in equipment, and bringing in expertise in technology, technique, and exploration. Although the mine is still viewed as a marginal performer due to its low ore grade, De Beers has identified several possible avenues for development that would keep the mine operating well into the future.

References

• Tassell, Arthur. African Mining Magazine. "Williamson - A Bright Future Ahead?" (http://www.mining.co.za/Williamson.htm). Brooke Pattrick Publications.
• De Beers Group official website. "De Beers Group: Tanzania" (http://www.debeersgroup.com/debeersweb/About+De+Beers/De+Beers+World+Wide/Tanzania/). Retrieved April 18, 2005.