The writings you find on my site, relating to Williamson Diamond Ltd, have been largely taken from a supplement produced by the Sunday News Magazine dated March 27 1966.

I give my thanks to the Sunday News for producing this excellent piece and I hope they do not mind (I don�t know if the paper still exists) but my parents found it amongst their personal effects nearly 28

years after leaving the Mine.

 The supplement has given me a start and it would be nice to get more information from past residents who would like to contribute to the site so please feel free to contact me by e mail or through leaving a

message in our Guest Book.

S. Maughan

Doctor John Thoburn Williamson

Doctor John Thoburn Williamson was a rugged Canadian geologist who, after he left the employ of De Beers in 1932, cycled north and began prospecting on his own for diamonds in what is now Tanzania.

In 1943, Dr. Williamson intrepidly traced a mineral often found in association with diamonds back to its source at Mwadui, where Williamson uncovered the largest diamond mine that had ever been found. The oval-shaped volcanic pipe, which was filled with diamondiferous ore, covered some 361 acres on the surface; and it was four times larger than any of the diamond pipes found in South Africa.

A De Beers team of prospectors had explored the territory around Mwadui a decade earlier without reporting any trace of diamonds. Now De Beers had to prevent Williamson from flooding the market with these diamonds. When the extent of the diamond strike became clear in 1945, Ernest Oppenheimer offered Williamson 2 million pounds sterling for the mine. Even though this was an enormous sum of money then, and Williamson himself was penniless, he turned down the offer. After spending ten years on the plains of Africa in solitary pursuit of diamonds, he was not about to sell out. He wanted to build his own empire. With the backing of a number of Indian merchants and a task

force of Italian prisoners of war, he began excavating the diamonds from the pipe. By 1946, he had some 6,000 workers living with their families at Mwadui, and over 200 armed guards protecting his budding empire. The entire encampment was surrounded by two barbwire fences and protected by primitive gun fortifications.

As the diamonds began to pour out of Mwadui, De Beers became increasingly concerned about its ability to control world prices. The corporate minutes of De Beers on June 20, 1946, reflect this growing apprehension. Sir Ernest Oppenheimer the chairman said that he was sure that a satisfactory outcome would result from negotiations with the British Colonial Office over a prospecting license for De Beers, but he said that the position would not be secure until they were able to come to terms with Williamson. He mentioned that the Tanganyika production was now one and one-half million pounds per annum. He very much doubted whether, at the moment, he had 65 percent effective control of world production. Oppenheimer pointed out that this uncontrolled production could prove embarrassing if there was an economic recession, and he recommended, according to the notes of the meeting, "that their efforts should be energetically directed towards obtaining effective control of all African production."

The diamond sights in London proved to be one effective means of reasserting control of the Mwadui diamonds. Dr. Williamson had to sell the low as well as high quality diamonds he mined to diamond cutters in order for his mine to be profitable. Most of the major cutting factories, especially for the more difficult-shaped diamonds, were clients of De Beers. When these clients came to the London sights, they were told, according to reports reaching the U.S. Department of justice, that they should not buy any of Williamson's diamonds. The threat was implicitly made that they might find their consignment drastically reduced or even abruptly ended if they bought any diamonds from Williamson. Since few of the cutting factories in Antwerp were willing to risk their sight in London by violating this rule of the game, Williamson found that he could only sell the clear, octahedron crystals that were in demand by small, independent cutters. He had to store most of the clear diamonds. This severely squeezed his cash reserves.

De Beers also applied pressure on Williamson through the British Colonial Office. When its representatives privately advised the British Exchequer of its stockpile of diamonds, De Beers quickly brought pressure on the Colonial Office to remedy the situation. Diamonds, after all, earned at that time more foreign exchange for Great Britain than almost any other export. At about this time, Colonial Secretary Arthur Creech Jones advanced the idea to nationalize the Williamson diamond mine. In an official white paper, Creech Jones suggested that the colonial government, through nationalization, might better be able to control the exploitation of a mineral resource than a private company.

For Williamson, the message was clear: Either he make his deal with De Beers or his mine might be nationalized. Finally, in August of 1947, Williamson acquiesced to these pressures, and Creech Jones announced in the House of Commons that Williamson had agreed to sell his entire output through the Diamond Trading Company in London. Williamson was now part of the arrangement.

 

Dr John Williamson always said that there were diamonds around Shinyanga. For years he scoured the area, often racked by fever or suffering from the effects of the sun that beats down day after day on the

shelterless scrub.

Then, on March 6 1940, he discovered Mwadui - certainly the richest and only major diamond mine there will ever be in East Africa.

The man who made the discovery which now results in multi -million pound revenue for the Government of Tanzania every year, was born at Montfort, Quebec in 1907, the son of a lumberjack of

Irish descent. He graduated in geology and mineralogy at McGill University, then took a post in his native province with the Quebec Geological Survey.

Claims

At the age of 21, Dr Williamson made his first visit to Africa, accompanying a professor from McGill University who had been appointed geologist to a gold mine in South Africa.

It was while working on the Rand that he was first bitten by the diamond bug.

He evolved a theory that somewhere in East Africa there was the original "pipe" through which diamonds were pushed to the surface from the subterranean cauldrons where they were formed.

In addition, he felt that such a "pipe" could be located by careful study of general land formation. It was this theory, and certainly not luck, which led him eventually to confine his search to within a 100

mile radius of Shinyanga. Even then it was a further 6 years before the riches of Mwadui were proved.

It was in 1956, when developments at the mine were at a particularly exciting stage, that Dr Williamson first became ill - perhaps the result of his arduous years of search in the bush.

Despite treatment at leading clinics in Canada and Britain, and a lengthy world cruise, he died at Mwadui in 1958. Although he had amassed a great fortune, Dr Williamson had become known as the

"world's loneliest bachelor".

At the time of his death, aged almost 51, Dr Williamson had poured back about �8,000,000 from his profits into the mine.This vast sum had gone towards providing equipment for the mining and treating

departments, a power station, water system, workshops, houses, roads, schools and churches.

Famous

He thought not so much of making profits as creating something of permanent value to the country in which he had made his home. He was greatly greatly concerned for the welfare of those who worked

for him.

In August 1958, arrangements were completed whereby the Government of Tanganyika and De Beers Consolidated Mines Ltd became joint owners of the entire share capital of the company. This was on

the understanding that none of the profits found their way to S. Africa.

A memorial to Dr Williamson stand over his grave in the quiet little cemetery at Mwadui - the town that he created.

 

The Mine

Since the search for diamonds began in Mwadui in 1940, a total of around 28,000,000 tons of soil, rock & gravel has been shifted to find them.

Yet despite this colossal effort, the riches yielded by the Williamson Mine could still be loaded

There are other ways of illustrating the challenge that recovering a tiny diamond from the African earth represents. It is estimated that the proportion of Diamonds to waste material in the Mwadui

deposits of the order of one to 30,000,000 by weight.

On a good day, the mine could be expected to yield 2,000 carats from 10,000 tons of waste material. ( One metric carat weighs 0.2 of a gram).

Waste

At the end of 1965 a total of 7,700,000 carats had been recovered from 26,584,426 tons of earth shifted. The collective weight of these diamonds was 3,400 lbs.

1965 was a record one for the mine. From 2,919,255 tons of earth shifted, came 742,042 carats. This topped the previous record by about 100,000 carats.

Because it is necessary to move such vast tonnages of waste materials, mining at Mwadui is on a large scale. A high degree of mechanisation is called for and techniques kept up to date.

Mining of the diamond-ferrous (diamond bearing) ground is by open cast methods and takes place from the grass roots down. Over the "pipe", a volcanic plug which carried the diamonds towards the

surface, 25 foot benches are mined by means of face shovels and "walking" draglines.

The draglines are fantastic contraptions, looking as one would imagine a lunar vehicle of the future. They are gigantic, each weighing over 200 tons and costing more than �100,000 each. Despite their

bulk, they can actually manage a cumbersome clanking "walk" on strong steel legs.

Mwadui's "pipe" has the largest surface area of any yet discovered in the world covering 347 acres. The deepest opencast working at present is 130 feet below the original ground level.

A program was started in 1958 to explore deep down into the pipe in an effort to ascertain whether it contained economic deposits of diamonds at lower levels. A shaft was sunk close to the "pipe" to a

depth of 1260 feet and tunnels driven from the shaft, and an adit to the open cast workings at 120, 300 and 1200 feet.

Tunnels

More than 50,000 feet of tunnels were driven and sampled but results below the 120 foot mark were not encouraging and the shaft has now been closed. However, if in the years to come diamonds become

scarce, with a consequent rise in their value, the possibilities of working at much deeper levels may well be considered once again.

Heavy disel trucks of up to 30 tons capacity carry the ore from the mining areas to a central crushing station. Some of these trucks cost over �20,000 and one back tyre can cost in the neighbourhood of

�600.

At the central crushing station the ore is ground down to a size which will enable it to be passed through the rest of the plant. It is then carried to the treatment plant along a 9,300 foot conveyor belt

system.

  

Stages

The main treatment plant is one of the most modern and up to date in the world. It is operated around the clock for 6 days of the week and then on the seventh day all necessary maintenance work is carried

out.

It is essential that the plant runs smoothly and that a constantly high rate of diamond recovery is kept up. This is in fact achieved and the recovery efficiency is put at 98 percent or perhaps even higher.

To whittle the 9000 tons or so of ore which pass through the plant every day down to a few pounds of material bearing the diamonds, a process of elimination is employed.

The first stage makes use of the relatively high specific gravity of the diamond, and thereby sorts out about 98 per cent of the waste material. After scrubbing, cleaning and sizing, the ore is passed through heavy media separators where diamonds, and certain other heavy materials, sink while other lighter

minerals are floated off to waste.

In the second stage, where the properties of extreme hardiness of the diamond is utilised, the heavy materials which sank in the first place are subjected to milling with steel balls. The soft minerals are reduced to pulp but the diamonds and a few other hard materials remain intact. This product is then

split into course and fine fractions for further treatment.

Fraction

The course fraction is preconditioned to make the surfact of the diamonds water repellent before it is passed over lengthy belts which have a thick layer of grease on their surface.

Diamonds adhere to the grease but the rest of the minerals, having a coat of water on the surface of the particles roll off the grease.

The fine fraction is driven and passed through an electrostatic field of 30,000 volts which is maintained between positive and negative electrodes. The diamonds, being poor surface conductors of electricity,

are not attracted to the positive electrode, and are split away from the rest of the material.

As a result of this ingenious process of elimination at the end of the day perhaps 20lbs of material remains from the thousands of tons fed into the plant. This is then hand sorted and the diamonds

plucked out with tweezers.

Over �1,800,00 has been spent on outside prospecting during the past six years. The bulk of this expenditure, some �1,750,000 has been financed by way of a loan from De Beers Consolidated

Diamond Mines. The payment of interest on the loan and repayment of the loan itself are contingent on the discovery and profitable exploitation of diamonds in the prospecting areas.

However apart from the small find in Kahama District, the chances of locating economic deposits of diamonds in Tanzania seem slim from results obtained to date.

Mwadui Worker

Tanzania's last diamond discovery of any economic importance was made at an isolated spot in Kahama District in 1963.

Mr. Abdul Amani, a Williamson Diamonds employee, took a sample of soil Nyangwhale and sent it for testing. In the laboratory it was found to contain evidence of diamonds.

Follow up sampling by geo-physical methods and pitting revealed that there were four small diamond deposits in four kimberlite pipes.

This find is well to the east of all other known kimberlite occurrences in the Shinyanga-Nzega area.

The main area of kimberlite, although diamond ferrous, does not appear to carry diamonds in economic quantities. But gravel's overlaying the kimberlite are enriched in places.

When the recovery plant is functioning at Kahama, perhaps towards the end of this year (1966), it is estimated that the daily throughput of one will be around the 1,000-ton mark.

At first glance the anticipated return of 11 carats per 100 tons looks very encouraging. However the diamonds at Kahama are not of particularly high quality, which means that they will not fetch a good

price on the world market.

The life of the Nyanwhale mine is expected to be brief - perhaps less than 5 years. But, as with Alamasi, it will be a good source of employment for local people and earn some foreign exchange for Tanzania.

At Isaka, near Igusule siding, 70 miles south of Mwadui on the Tabora-Mwanza line, Williamson Diamonds hold the right of occupancy over 250 acres of forest land and adjacent lime claims.

Accommodation has been provided for a workforce of about 30 and lime kiln, several charcoal kilns, and storage sheds have been built.

It is the source of supply of the company's total requirements of lime, used in the heavy media separation plant at Mwadui; also wood and charcoal used in underground developments are obtained

there.

Operations are controlled from Mwadui, and the only difficulties are in obtaining sufficient empty wagons in which to send products to Mwadui.

 

Record Borehole

A new world record for diamond drilling has been established in a Transvaal, S. Africa mine- a borehole almost 3 miles deep.

Drilling with a 20 year old twin hydraulic drill - originally designed to go 6,000 feet.

 With the mass of machinery that clatters away for 24 hours a day to keep Mwadui working, there are many things that can go wrong.

Breakdowns may be on a large scale or annoyingly intricate but they have to be fixed on the spot.

Mwadui is remote and to send away for spare parts would take more time than the mine could spare- even if the necessary part were easily obtainable, which is doubtful. Therefore, to ensure that the mine keeps running

smoothly, an efficient engineering department is vital.

Power

The engineering department at Mwadui is large and well equipped, and one third of the mines total workforce is employed there. Employees in the department can never complain that life is dull with the variety of problems they

are called upon to overcome.

During the course of a day's work they might be asked to repair a hole in one of the huge buckets attached to "walking" draglines, panel beat a battered vehicle or, in the case of one man, make an artificial limb.

The engineering department deals with the manufacture maintenance and civil engineering construction. It is responsible for the generation of power to the 12.3 megawatt diesel-driven station, water requirements amounting to

120 million gallons or more per month, sewerage disposal, refrigeration, public transport, aircraft maintenance, radio and telephone communications and maintenance for buildings and roads.

Mwadui's power station is one of the biggest in Tanzania. In addition to meeting the tremendous needs of mine machinery, it lights the whole of Mwadui township and sends a supply to nearby Shinyanga.

The mine's artificial limb maker-not a full time job- is Harry Maughan, a long service man at Mwadui. Most of the limbs he has made have been for children who have fallen victims to polio or who have lost arms and legs in

accidents.

Limited

Mr. Maughan made his first artificial limb about six years ago, with only a very limited knowledge of how it should be done and just an ordinary set of workshop tools to do it with.

During his last leave in England he attended a short training course at Roehampton Hospital, which specialises in the fitting and manufacture of artificial limbs.

There was mutual amazement at Roehampton. The experts were amazed that Mr. Maughan could make such efficient limbs using the methods that he had, and Mr. Maughan was amazed that he had managed it when he was

shown the way that it should have been done.

The limbs he makes now have a professional touch, although there are several children running happily around Mwadui today who have reason to be grateful for his earlier efforts.

The Restaurant

  You would hardly expect to find a first class restaurant in a particularly remote part of Tanzania.

To be greeted by a man who has created delicious dished in many parts of the world would be even more unlikely - yet both these surprises are in store for you at Mwadui.

Mining town myths about workers who exist on a diet of beans and salt bacon eaten in highly unwholesome surroundings will quickly be dispelled by visiting the premises of Mr. Egbert Van Buuren and his wife run at Mwadui. Famous people,

who have dined at some of the world's most lavish restaurants have eaten there and been impressed.

Mr. Van Buurens visitors book bears testimony to this. His guests have included Princess Margaret, several heads of state, and many diplomats.

In each case he tries to give distinguished visitors a dish that is popular in their own country - a very dangerous thing to do unless you are an expert.

 

Talented

However, after almost 40 years in the catering business, Mr. Van Buuren can certainly be rated an expert, and his guests are usually delighted. There was an example of this recently when a party of Chinese visitors were astounded to find that a

complete dinner, made up of their national dishes, had been laid on for them.

V.I.P's are not the only one's to benefit from the talented touch that Mr. Van Buuren and his staff have with food. Mine employees who eat regularly at the restaurant say that it is a case of never a dull meal. "You should just taste the steak and

kidney pie" breathed one customer reverently.

Mr. Van Buuren began his career in Rotterdam. As a young man he worked for KLM (Dutch Royal Airlines) in both Holland and Java, before joining a shipping line. Then he went onto the Piscardero Bay Club at Curacao in the West Indies.

In 1950 Mr. And Mrs. Van Buuren came to Tanganyika. They worked first at the now non-existent Beatrix Hotel at Kurasini, before going onto the Beach and Ras Bura hotels at Lindi. Then they came back to Dar es Salaam to organise

catering at the New Africa Hotel until 1955 when Dr Williamson persuaded them to join him at Mwadui.

Favourite

"I remember that the Doctors favourite dinner was a fresh sea food dish followed by chocolate sponge cakes. He also had a magnificent wine cellar" said Mr. Van Buuren.

Mrs. Van Buuren is a great admirer of Tanzanian dishes. She believes that Tanzanians have a flair and imagination that is seldom recognised where cookery is concerned. Her own favourite dishes are chicken cooked in coconut milk and curried

goat.

The sign of the Chaine des Rotisseurs is displayed outside the Restaurant at Mwadui. This organisation was formed several centuries ago to maintain the fine traditions of French cooking. The Van Buuren's recently became members and in their hands there can be no doubt that cooking of whatever type, whether it be French or Chinese, will be of the highest order.

 

Security

Diamonds are said to be a girl's best friend and they also have quite an attraction for the criminals of this world.

However, anyone at Mwadui who might be tempted to make a quick profit through illicit diamonds usually thinks again on remembering the ferocious dogs, electronic eyes and vigilant policemen, that are always on hand - waiting for him to make

the slightest mistake.

The security system at Mwadui is ultra efficient. It would be virtually impossible to prevent the theft of a small stone here and there. But the chances of getting away with a worthwhile haul are extremely slim.

Security at Mwadui is the responsibility of the Diamond Protection Division of the Tanganyika Police.

It used to be controlled by the company but this proved to be an unsatisfactory arrangement. However, Williamson Diamonds meet the cost of maintaining 200 or more policemen on the mine, their transport, free accommodation and other

amenities.

They also have provided a canteen, recreation hall, armoury, bandstand, parade ground, and sports fields and dog kennels.

Dogs have proved particularly successful in the campaign against crime. The Ridgebacks, Dobermanns and Alsatians at Mwadui are an exceptionally fierce collection. They are used most effectively to ambush raiders who attempt to enter the

security and mining areas.

Television

The electronic eyes, which are actually remote controlled television cameras, have been installed at vulnerable places in the mines industrial complex: places where a diamond can be distinguished from a surrounding ore, perhaps thereby tempting a

human hand to grab it.

Whatever the electronic eye can see is beamed to a central control room, and monitored on a series of television screen's.

Policemen at Mwadui never take a chance. They too guard vulnerable points and always bar the way to important areas of the mine. Every mine employee, no matter how well known or important he may be, is carefully watched on entering or

leaving such areas.

Before they can even consider outwitting electronic eyes, policemen or dogs, criminals have first to get into the security area - not an easy task.

It might have been easier a few years ago when a 15-mile fence of barbed wire and wood surrounded the mine. But it has now been replaced by a double ring of diamond mesh apron fences which Police cars can patrol along an all weather road.

Two inner security areas are fenced off separately, one around the treatment plants and the other around the industrial area and opencast workings. Check points are established to reduce access to those areas to workers who are actually employed

there.

Laminated plastic identification passes have been issued to all employees and their dependants.

These must always be carried and ensure that tight control is maintained over movement into and out of the township.

 

The Hospital

Some of the finest medical facilities to be found anywhere in Tanzania are available to staff in Mwadui and to residents of the surrounding areas.

The mine hospital is well equipped and staffed with highly trained personnel. As a result it is possible to carry out intricate operations there which might otherwise have to be performed at specialist hospitals.

Kept Busy

Mr. A. Nurick, the surgeon in charge of Mwadui Hospital, has been there for nine years. In addition to carrying out regular operating sessions there, he also operates at the hospital in Shinyanga, and at the nearby mission hospital.

Quite a large percentage of the patients treated at the mine hospital come from surrounding areas. If they can afford it they are asked to make a payment in ratio to their income, but often they have little or no money.

This means that the hospital is very busy but, as Mr. Nurick explained, "By helping people from outside the mine we are also helping ourselves.

Many of the staff here are young and have to undergo a medical examination regularly. As a result general healthy standards here are high and if we confined ourselves merely to treating them there wouldn�t be much work to do at the

hospital.

"This could mean that staff would have little to do and might start to lose interest. As it is, being busy keeps us up to the mark all the time."

  

Education

There is a very comprehensive educational system in operation in Mwadui. They have everything there - except a secondary school - and one of those is now being built only a mile outside the mine gates.

Impressive progress has been made at Mwadui's Swahili medium primary school, which has been gradually enlarged and upgraded. At the moment it provides education up to Standard V111, has 28 teachers and an average daily attendance of

over 800 pupils. By 1968 it is anticipated that this total will have swelled to top the 1,000 mark.

The English speaking medium school caters mainly for children from English speaking homes or from non-English speaking homes where parents wish their children to study in this language. At present there are 123 pupils at this school,

of which about half come from non-English speaking homes.

School visits

Nursery schools have an enrollment of about 450, which means that more than 55 per cent of the 2,500 or so children who live at Mwadui attend school. Under normal circumstances every pupil entering Standard 1 has the opportunity of being

educated to Standard V111 as a matter of course.

The school outside the gates, the Shinyanga Secondary School, is now being built. Students from Mwadui schools will be able to compete for places there.

Children at the neighbouring Alamasi Mine are not neglected. There are lower primary facilities there for 50 children. And 20 older pupils are brought into Mwadui every day for their education.

Conducted educational tours of the mine are arranged weekly for children over 12 from schools and other educational institutions in nearby regions.

Since 1962, a total of almost 2,000 children have made such visits.

 

Neat Homes and Happy Children

Mwadui township should have more than it's fair share of model Tanzanian citizens.

For several years now it's residents have been able to benefit from an extensive community development campaign, designed to create an active, healthy life for them all.

In the main the people of Mwadui have been eager to learn about the art of living together. As a result, their social lives are thriving, homes are generally neat and well cared for, and children healthy and happy.

The principal aims of those associated with community developments at Mwadui have been to establish a balanced urban community and help it's members through talks, publications and other forms of training to acquire the sentiments and

values needed to live in an environment which was strange to many.

Problems

A large proportion of the employees of Mwadui had never before lived in a town, and needed this kind of help to overcome the new problems they faced.

Excellent facilities such as schools, churches, a mosque, shopping center's and a large community centre, have made a great contribution towards the success of the scheme so far.

Budgeting and the running of a home have had a great emphasis placed on them. At one time Un-skilled and semi-skilled employee's part of their payment in kind, with free issues of such thins as meat and firewood. However as part of the

community development plan, it was decided that this system should be abolished, and payment in kind made up for in a wage increase.

Education

As a result, shops have replaced the old ration stores, and people have learned to be provident and budget for themselves.

Housewives have been helped a great deal through the scheme. Many have been taught the simple arithmetic of simple household and market place, to read and write, to make and repair cloths and how to care correctly for a child. As a result

their homes are efficiently run.

As is the case throughout Tanzania, many of the older workers never had the chance of a basic education. At Mwadui they are now being given this chance - and are taking it eagerly.

Even after a hard day at the mine, male workers still crowd into the classrooms for their evening lessons, while women and night workers are taught during the day.

 

Swimming

There are several pleasant bars and beer gardens for the employees to enjoy. At one of these, an average of 4,000 gallons of pombe is drunk every month. This is brewed within Mwadui at one of the most modern and hygienic pombe breweries in

East Africa.

Sport is extremely popular at Mwadui. There is a fine nine-hole golf course, three swimming pools, numerous tennis courts, a squash court and several soccer pitches. There a number of social clubs, frequent cinema shows, and a photographic

society, as well as the usual dances and concerts.

Two monthly magazines "Habari za Mwadui" and "The Mwadui News" are sponsored by the company.

They incorporate news and educational features, social columns, letters from readers, and programs for social and sporting events.

 

THE GERMANS LEFT A FORTUNE UNTAPPED

There were rumours of the existence of diamonds in the region south of Lake Victoria before the 1914-18 war, but this has never been confirmed and nothing is known of any German diamond mining activities In Tanganyika.

After the war, in 1921, prospecting for diamonds began but it was not until 1925 that any exports were made. During the next few years , most of the diamonds came from the Mabuki mine, 36 miles south of Mwanza in Kwimba District.

Claims

In 1927, exports exceeded �100,000 in value almost wholly from the Mabuki deposit. A great meant other claims were pegged in the immediate neighbourhood, but little came of these speculations. In the same year prospecting began nearer to Shinyanga and stones were reported from Usogoro. In 1928, the Kizumbi deposit just south of Shinyanga town was under

investigation and during that year nearly 1,500 carats were recovered.

Claims are still held on this deposit by Williamson Diamonds Ltd. This discovery resulted in a further rush of claim pegging.

The first presentation of a stone to Royalty is recorded , when during the visit of the Prince of Wales in 1928, a 7� carat stone was presented to him as a memento of the territory.

In 1929 the production of diamonds began to decline, and despite considerable prospecting, the decline continued through 1930.

In 1929, pipes and gravels in the Singida District were examined but with no success, so that by 1932, exports were valued at only �1,859, and in the depressed state of the diamond market gave little encouragement to prospectors.

Production from the Mabuki and Kizumbi deposits and a few minor prospects continued in a small way for the next few years but exports never exceeded 3,500 carats until 1939, when exports increased to 3,387 carats valued at �12,255.

 

Famous

In 1940, Dr. Williamson discovered the Mwadui deposit, and from that date diamonds began to assume an increasingly important position in Tanganyika's mineral exports. The rest of the history of diamonds in the territory is virtually the

history of the Mwadui deposit.

Individual stones weighing 120, 142, 172,174, 181 and 240 carats have been recovered in recent years from Williamson Diamonds Ltd.; the later being valued for royalty purposes at �27,685.

The most famous stone is undoubtedly the "pink" diamond found in October 1947, a beautiful rose coloured "collectors piece" weighing 54.25 carats. It was presented to the then Princess Elizabeth on the occasion of her marriage and when cut

yielded a jewel of 23.6 carats, which is unrivalled amongst world famous diamonds on the account of it's unusual colouring, and is literally priceless by usual commercial standards.

The mine's exports for 1965 are provisionally given as 501,984 metric carats valued at �4,231,000, while the figures for the whole of Tanganyika were approximately 515,927 metric carats valued at �4,271,000.

 DeBeers

 To perpetuate the diamond invention, it was not sufficient for De Beers merely to own the large mines that produced most of the world's diamonds. It had to control the production from all other significant sources, including the scattered diggings in Africa and the jungle streams of South America. It had to be able to assure the major diamond cutters and dealers that they had no alternative source for their diamonds other than De Beers' operation at Charterhouse Street in London. If its clients believed that it would be possible to buy diamonds from diggers, tribesmen, smugglers and small mine owners, De Beers could no longer compel them to adhere to its rules for avoiding price competition.

Oppenheimer therefore negotiated a series of secret arrangements to block the availability of diamonds from the sources his company did not directly own or control. In South Africa and the Belgian Congo, he pressed the governments into passing laws that forced independent prospectors and diggers to sell their diamonds only to government-licensed diamond buyers, who in turn contracted to sell their diamonds to De Beers' subsidiary, the Diamond Trading Company. In British colonies, such as Sierra Leone, he contracted to buy whatever diamonds were unearthed from British mining companies, such as the Selection Trust, which held the mining concessions there. In South America, where the alluvial diamond fields were scattered over vast areas, he arranged deals with local buying agents to buy up loose diamonds. In all cases, Oppenheimer required that the total production of diamonds be turned over to De Beers or its subsidiaries at an agreed-upon price.

When diamonds were found in the British colony of Guiana in 1925, De Beers, acting through its diamond syndicate in London, made an arrangement to buy the entire production, which amounted to about 12,000 carats a year. The agreement, drawn up by Otto Oppenheimer, specified that the price paid by the syndicate for these diamonds would be established through a sorting procedure. Moreover, it was stipulated that Oppenheimer would be the "technical advisor" to the diamond miners, and, as such, he would be solely responsible for defining the assortment. According to the contract, Oppenheimer's decision on the sorting could not in any way be questioned or redressed. This meant, in effect, that Oppenheimer could determine what price would be paid to the Guianans, and if they found the price too low, they were restricted by the contract from selling the diamonds to anyone else.

As De Beers found that its own mines were producing more diamonds than it could market, its interest in this arrangement was not to stimulate further production in South America but to prevent these diamonds from finding their way into the market at an unfortunate time. Once the contract was signed, Oppenheimer began adjusting the sorting procedures by creating grades of "finer" diamonds. This maneuver effectively reduced the average price paid by the syndicate for Guianan diamonds by over 50 percent. At these low prices, the Guianan mining company, United Diamond Fields of British Guiana, Ltd., could no longer afford to buy diamonds from the native diggers. Consequently, the company's production, which was based entirely on what these diggers found and turned in, fell from 12,000 carats to 3,000 carats a year. Bound by its

contract to accept the syndicate's price, the company went bankrupt in 1927, and Guiana diamonds ceased to be a threat to De Beers. The details of this arrangement emerged only in 1932 when a director of United Diamond Fields sued Otto Oppenheimer for fraud. After demonstrating that Oppenheimer had falsified an important certificate of evaluation, the director's lawyer, Sir Patrick Hastings, forced the syndicate to pay his client a large cash settlement. There was, however, one maverick geologist who refused to accept this crucial arrangement, Doctor John Thornburn Williamson. Williamson was a rugged Canadian geologist who, after he left the employ of De Beers in 1932, began prospecting on his own for diamonds in what is now Tanzania.

In 1943, Dr. Williamson intrepidly traced a mineral often found in association with diamonds back to its source at Mwadui, where Williamson uncovered the largest diamond mine that had ever been found. The oval-shaped volcanic pipe, which was filled with diamondiferous ore, covered some 361 acres on the surface; and it was four times larger than any of the diamond pipes found in South Africa.

A De Beers team of prospectors had explored the territory around Mwadui a decade earlier without reporting any trace of diamonds; now De Beers had to prevent Williamson from flooding the market with these diamonds. When the extent of the diamond strike became clear in 1945, Ernest Oppenheimer offered Williamson 2 million pounds sterling for the mine. Even though this was an enormous sum of money then, and Williamson himself was penniless, he turned down the offer. After spending ten years in the jungles of Africa in solitary pursuit of diamonds, he was not about to sell out. He wanted to build his own empire. With the backing of a number of Indian merchants and a task force of Italian prisoners of war, he began excavating the diamonds from the pipe. By 1946, he had some 6,000 workers living with their families at Mwadui, and over 200 armed guards protecting his budding empire. The entire encampment was surrounded by two barbwire fences and protected by primitive gun fortifications.

As the diamonds began to pour out of Mwadui, De Beers became increasingly concerned about its ability to control world prices. The corporate minutes of De Beers on June 20, 1946, reflect this growing apprehension. "The chairman (Sir Ernest Oppenheimer) said that he was sure that a satisfactory outcome would result from negotiations with the British Colonial Office over a prospecting license for De Beers, but he said that the position would not be secure until they were able to come to terms with Williamson. He mentioned that the Tanganyika production was now one and one-half million pounds per annum. . . . He very much doubted whether, at the moment, he had 65 percent effective control of world production." Oppenheimer pointed out that this uncontrolled production could prove "embarrassing" if there was an economic recession, and he recommended, according to the notes of the meeting, "that their efforts should be energetically directed towards obtaining effective control of all African production."

The diamond sights in London proved to be one effective means of reasserting control of the Mwadui diamonds. Dr. Williamson had to sell the low as well as high quality diamonds he mined to diamond cutters in order for his mine to be profitable. Most of the major cutting factories, especially for the more difficult-shaped diamonds, were clients of De Beers. When these clients came to the London sights, they were told, according to reports reaching the U.S. Department of justice, that they should not buy any of Williamson's diamonds. The threat was implicitly made that they might find their consignment drastically reduced or even abruptly ended if they bought any diamonds from Williamson. Since few of the cutting factories in Antwerp were willing to risk their sight in London by violating this rule of the game, Williamson found that he could only sell the clear, octahedron crystals that were in demand by small, independent cutters. He had to store most of the clear diamonds. This severely squeezed his cash reserves.

De Beers also applied pressure on Williamson through the British Colonial Office. When its representatives privately advised the British Exchequer of its he stockpile of diamonds, De Beers quickly brought pressure on the Colonial Office to remedy the situation. Diamonds, after all, earned at that time more foreign exchange for Great ,Britain than almost any other export, and the British government.. At about this time, Colonial Secretary Arthur Creech Jones advanced the idea to nationalize the Williamson diamond mine. In an official white paper, Creech Jones suggested that the colonial government, through nationalization, might better be able to control the exploitation of a mineral resource than a private company.

For Williamson, the message was clear: Either he make his deal with De Beers or his mine might be nationalized. Finally, in August of 1947, Williamson acquiesced to these pressures, and Creech Jones announced in the House of Commons that Williamson had agreed to sell his entire output through the Diamond Trading Company in London. Williamson was now part of the arrangement.

Oppenheimer went on to make similar arrangements with any other person, corporation or nation that discovered diamonds. He was in a position to either buy them out directly or to contract to buy all the diamonds their mines produced. It was a mutually profitable arrangement.

During Sir Ernest's lifetime, De Beers never discovered a diamond mine itself. Oppenheimer saw little point to investing profits in exploring for diamonds, since De Beers made its profits from a scarcity, not an abundance, of diamonds. As he established it, one of the cardinal principles behind the diamond invention was that demand for diamonds was fixed each year and varied only with the number of engagements.

Any sudden increases in the production of diamonds would therefore have to be added to De Beers' stockpile rather than its profit, and it made little sense for Oppenheimer to create new mines until the old ones were depleted. Instead, Oppenheimer reinvested the stream of profits into gold mines in the Orange Free State province of South Africa. The gold production would provide a reserve of capital for De Beers that would allow it to buy back diamonds if the retail market ever slackened.

By the time Sir Ernest died in 1957, he had turned the diamond invention into a powerful instrument for preserving the price of diamonds. By merging the mines in South Africa with the syndicate in London, he created a double-edged sword, production and distribution, for maintaining his control over the diamond industry. Through secret arrangements that he patiently and meticulously made with independent mine owners, he managed to channel almost all of the world's uncut diamonds through this system.

The Mwadui kimberlite was discovered by Canadian geologist Dr John Williamson in 1940. The kimberlite pipe covers 146 ha and ranked then as the largest economically exploitable pipe in the world � and indeed no other economic pipe of this size has been mined since. Dr Williamson developed Mwadui into one of the most famous diamond mines in the world. After his death in 1958, De Beers purchased fifty percent of the mine.

 

Although it is often thought that Dr Williamson discovered Tanzania�s first diamonds, the Williamson mine was in fact preceded by several tiny operations, including the Mabuki mine which Williamson worked on and later owned.

Williamson eked out a meagre living from Mabuki, which he used as the base for his prospecting operations in what was then known as Sukumaland. In 1940 in the Shinyanga area, around 160 km south of the town of Mwanza on Lake Victoria, he discovered the kimberlite, which would make his name world famous.  The site of the mine was named Mwadui � after a local chief � and in the years since the names �Mwadui� and �Williamson� have become virtually synonymous.With the Second World War in progress and with Williamson himself having few resources, development at Mwadui was initially slow but, by the 1950s, a formidable mine had emerged. The total staff and labour force numbered several thousand and included around 400 expatriates, mostly from the UK and South Africa. Williamson made his home at Mwadui and managed the operation very closely. Mining equipment included draglines and scrapers while a succession of treatment plants were built, the first being a pan plant running at a grade of 62 cpht. A notable innovation in the late 1950s was an HMS plant, which ranked as the first in the world in the diamond mining industry.Williamson died early. He contracted cancer and passed away in 1958 at Mwadui, aged 52. The mine passed into the hands of De Beers and the Government of Tanganyika on 13th August 1958 and was later, in 1971, nationalised by the Government of Tanzania (as Tanganyika had become after independence). Details of how the mine performed during the period of nationalization are sketchy, but it seems that in the 80s the mine�s health took a downward turn. The loss of expatriate skills, an inability to pare down a huge labour force, the declining grade of the ore body and a lack of maintenance or stay alive capital expenditure, all apparently contributed to a fall-off in performance.

In the early 1990s, De Beers was invited back to manage the mine and today Williamson Diamonds Limited (WDL) is owned 75% by De Beers and 25% by the Government of Tanzania. The first Managing Director of the restructured company was John Acland, who arrived at Mwadui in 1993 and who retired earlier this year. Tony Guthrie, who has vast experience in the De Beers Group, and who now has the challenge of steering Williamson into the future, has succeeded him.

 

Discovery of diamond-bearing kimberlites in Kalyandurg area, Anantapur district, Andhra Pradesh

Dharwar Craton with two well-known kimberlite fields – the Wajrakarur Kimberlite Field (WKF) in Anantapur district, Andhra Pradesh and the Narayanpet Kimberlite Field (NKF) in the western part of Mahbubnagar district, Andhra Pradesh and the adjoining Gulbarga district, Karnataka, forms a prominent kimberlite province in India. Seventeen known kimberlites of the WKF are distributed mainly in three clusters, viz. (i) The Wajrakarur cluster; (ii) the Lattavaram cluster, and (iii) the Chigicherla cluster and some isolated kimberlite bodies1. Ground surveys based on conceptual modelling and characterization of the kimberlite indicator minerals recovered during reconnoitary traverses led to the discovery of a hitherto unknown cluster of diamond-bearing kimberlites around Kalyandurg within the Hagari drainage basin in the southern part of WKF (Figure 1).

The area forms a part of the NNW–SSE trending, 500 km long and 25 km wide zone of post-tectonic granite called Closepet Granite. Two sets of mafic dykes trending NNW–SSE and ENE–WSW intrude the granite. The area is traversed by a number of NNW–SSE faults parallel to the regional trend of the granites and major ENE–WSW trending transverse faults.

Kimberlites, emplaced in the cratonized parts of the earth’s crust are essentially controlled by major deep-seated faults/fractures, whose reactivation has a bearing on their emplacement. While these form the regional controls, fault intersections, splay faults around fold closures and resultant fractures form the most ideal local controls for kimberlite emplacement2,3. The kimberlites of WKF were emplaced around 1100 m.y. period4. Nayak and Burhanuddin5 related the emplacement of kimberlites, in Eastern Dharwar craton to the reactivation of major crustal fractures around 1100 m.y. period.

A conceptual model, based on the disposition of known kimberlites of WKF in relation to their geological setting and tectonic milieu, supplemented by critical evaluation of the data emerging from study of geological maps, satellite imageries and aerial photographs, was visualized for locating new kimberlites, which envisaged that kimberlite emplacements in this field were controlled by major ENE–WSW faults, passing through the closures of structural domes and reactivated around 1100 m.y period. Intersection of these faults with NNW–SSE faults/fractures formed the favourable loci for kimberlite search. Evidences of reactivation of these faults are recorded in the sediments of the Nallamalai Group of the Cuddapah Basin. Satellite imagery

studies indicated that the ENE–WSW faults hosting the kimberlites of WKF extend further west up to the Chitradurga Schist Belt in Karnataka cutting across the Closepet Granite which is believed to have been emplaced along a major NNW–SSE trending fault6. The area around Kalyandurg marked by the intersection of these ENE–WSW faults with NNW–SSE trending contact of the Closepet Granite with the gneisses and also faults/fractures parallel to it was considered favourable for kimberlite emplacement.

 

Figure 2.  Photomicrograph of pipe KL-3 showing macrocrystal olivine (anhedral) and micro-phenocrystal olivine (euhedral) set in a fine grained groundmass of phlogopite, carbonate opaques and perovskite ppl (120 ´ ).

Based on this conceptualization, the first author took a few regional geological traverses and collected stream sediment samples in the area around Kalyandurg, mainly in the vicinity of the intersections of the ENE–WSW faults with NNW–SSE faults during 1995–96. Two of the samples collected from confined drainage basins, one near Bommaganapalli and the other near Timmasamudram near Kalyandurg, yielded chrome spinels of kimberlite affinity. Detailed geological traverses in the area south of the indicator mineral location near Bommaganapalli resulted in the discovery of three kimberlite bodies, two near Pillalapalli (KL-1 and KL-2) and one near Nagireddipalli (KL-3) (Figure 1).

Kimberlite KL-1, located about 1 km north of Pillalapalli village, is highly weathered and exposed in a well section and a canal cutting. Rest of the body is covered by about 2 m thick alluvium. Hard greenish-black kimberlite (hardebank) was intersected in a bore well. The weathered part exposed in the well section and canal cutting is yellowish-green and is highly carbonated with clearly discernible macrocrystic texture. Pseudomorphs of large rounded and small euhedral to subhedral phenocrysts of olivine are altered to serpentine or iddingsite. Macrocrysts of ilmenite measuring 1–2 cm are seen. In thin sections it shows typically inequigranular, brecciated texture with large rounded macrocrysts of olivine and ilmenite in a fine grained groundmass consisting of mainly euhedral to subhedral olivine, opaques, calcite, phlogopite, perovskite, diopside and garnet. Opaques are mainly ilmenite, magnetite and chromite. Perovskite is mostly associated with opaques. Panned concentrates of this rock indicated the presence of ilmenite, spinel, chrome diopside and garnet.

Kimberlite KL-2, located about 3 km east of Pillalapalli is capped by calcrete with a distinct tonal difference from the surrounding reddish-brown granitic soil. Calcretized kimberlite fragments consisting of olivine pseudomorphs, ilmenite, chromite and chrome diopside are seen in the calcrete capping. Olivine is completely replaced by carbonate. Macrocrystal ilmenite measuring about 1 cm is common. In thin section, the kimberlite shows an inequigranular texture with pseudomorphs of large rounded olivines in a fine grained groundmass consisting of pseudomorphs of euhedral to subhedral olivine, opaques, clinopyroxene, phlogopite and perovskite. Opaques are ilmenite and chromite. Heavy mineral assemblage includes garnet in shades of lilac, mauve and orange-red, spinel, ilmenite, chrome diopside and corundum.

Kimberlite KL-3, located about 1 km north-west of Nagireddipalli, comprises both weathered kimberlite and hardebank kimberlite. The body is covered by a calcrete capping with the hardebank variety occurring as a few small, detached outcrops. The hardebank variety is melanocratic and inequigranular with large rounded grains of olivine and ilmenite and country rock fragments in a fine-grained groundmass imparting a brecciated texture to the rock. In thin sections, it shows large rounded macrocrystal olivine and ilmenite in a fine-grained groundmass consisting of mainly euhedral to subhedral olivine, clinopyroxene, perovskite, phlogopite and opaques (Figure 2). The opaques are ilmenite, magnetite and chromite. The olivine is altered to serpentine and calcite. Panned concentrates of this body yielded ilmenite, spinel, chrome diopside and garnets. Some of the ilmenite macrocrysts are seen coexisting with clinopyroxene.

Chemically the three kimberlite bodies are typically undersaturated in SiO2 and are comparable with pipes 1, 6, 7 and 10 of WKF (Table 1). These kimberlites fall in the classical kimberlite field of Bergman7 in the ternary plots involving Al2O3–FeO–MgO and K2O–MgO–Al2O3.

Preliminary studies indicated the presence of mantle nodules comprising garnet harzburgite, garnet lherzolite, diopside lherzolite and kyanite eclogite which range from a couple of cm to as large as 8 cm in diameter. While the pipe KL-1 yielded garnet lherzolite and garnet harzburgite nodules, pipe KL-2 yielded kyanite eclogite and garnet lherzolite nodules.

Panned concentrates of about 50 kg of kimberlite material from pipe KL-2 yielded one micro diamond – a white broken chip with cleavages – thus establishing the diamondiferous nature of this kimberlite body. These are the first kimberlites recorded in the Hagari drainage basin. It is quite likely

that these kimberlite bodies constitute part of a major cluster forming the primary source for the large diamonds being picked up by local villagers around Kalyandurg and also in older gravel patches in the Hagari River basin.

1. Satyanarayana, S. V., Rao, K. R. P., Sivaji, K., Nayak, S. S. and Ramalingaswamy, G., Indian Mining Summit ’97, Hyderabad, 1997.2. Mitchell, R. H., Kimberlites: Mineralogy, Geochemistry and Petrology, Plenum Press, 1986, pp. 105–135.

3. Janse, A. J. A., International RoundTable Conference on Diamond Exploration and Mining, New Delhi, 1992.

4. Anil Kumar, V., Padma Kumari, V. M., Dayal, A. M., Murthy, D. S. N. and Gopalan, K., Precambrian Res., 1993, 62, 227–237.

5. Nayak, S. S. and Burhanuddin, Md., Geol. Surv. India Spl. Publ. No. 40, 1996, pp. 19–29.

6. Swami Nath, J., Ramakrishnan, M. and Seshadri, T. S., Mem. Geol. Surv. India, 1981, 112, 79–87.

7. Bergman, S. C., Geol. Soc. Spl. Publ. (eds Fitton, J. G. and Upton, B. G. J.), 1987, 30.

8.  

9. Dawson, J. B., Kimberlites and their Xenoliths, Springer Verlag, New York, 1980.

10. Rao, K. R. P., Dhakate, M. V., Chowdary V. S., Bhaskara Rao, K. S., Satyanara-yana, G., Nayak, S. S. and Reddy, T. A. K., Rec. Geol. Surv. India, 1998, 131, PT-5, 39.

ACKNOWLEDGEMENTS.  We thank Shri G. Ramalingaswamy, Geologist (Sr) (Retd.) for his guidance in photogeological and satellite imagery studies, in developing the working model. We also thank Shri K. R. P. Rao, Geologist (Sr) who scanned the heavy mineral concentrates and recovered the microdiamond, Shri S. Neelakantam, Director and Dr K. S. Rao, Dy, Director General, Operations Andhra Pradesh for their unstinted support and constant encouragement in the regional studies for locating new kimberlite areas, and Dr S. K. Mazumder, Dy. Director General, GSI, SR, for permission to publish this work.

S. S. NAYAK

S. A. D. KUDARI

Operations Andhra Pradesh,

Geological Survey of India,

Hyderabad 500 068, India