The alluvial diamond deposits of the Central African Republic (CAR) are mined almost exclusively by way of informal artisanal and small-scale mining (ASM) methods. ASM sites range in diameter from a few meters to 30 meters or more, and are typically excavated by crews of diggers using hand tools, sieves, and jigs. CAR's reported annual production …

The Punch Jones Diamond—also known as the Horseshoe Diamond —remains the largest alluvial diamond ever discovered in North America and the third largest found on the continent. Grover Jones, Sr., fathered 15 boys and a daughter, the youngest, in Monroe County. According to the late historian Shirley Donnelly, the gem …

The discovery of diamonds in South Africa in the late 19th century also led to the establishment of large-scale alluvial diamond mining operations in the country. Nowadays, it is most commonly carried …

Alluvial diamond properties of any scale can be evaluated to conform to any of the internationally accepted resource estimation codes. A complete understanding of …

Alluvial diamond mining is an above ground form of mining which concentrates on gathering diamonds on the surface. This is the most traditional and oldest mining method in the diamond industry, which …

The general principles that govern any search for alluvial diamonds, the processes involved in alluvial diamond deposition and the methods and technology …

Alluvial diamonds were discovered in 1859 in South Africa and in 1869 mining of the hard rock sources of diamonds started at Kimberley, the capital of the Northern Cape Province of South Africa. The biggest and most precious diamond ever found was discovered in 1905 by Frederick Wells, Manager of the Premier Diamond …

Diamonds are found in three types of deposits: alluvial gravels, glacial tills, and kimberlite pipes. The kimberlite pipes (such as those at Kimberley, South Africa) form from intrusions of magma into the Earth's crust and deliver diamonds and other rocks and minerals from the mantle. The pipes themselves are often less than 100 million years old.

Transported by rivers and streams, these diamond crystals end up in river gravel beds and silt often at great distances from their original source. Until the late 1800s, the world's diamonds were found and collected from these alluvial beds. Today, most diamonds are found in kimberlite pipes, which are the primary source of mined diamonds.

The alluvial diamonds associated with the gravel deposits in the Christiana, SchweizerReneke, Wolmaransstad and Bloemhof districts are generally of high quality, as a result of the presence of larger stones (50 to 200 ct). In recent years there have been important advances in the techniques used for the exploration of alluvial diamond …

Abstract. Since the mid-1950s the Kwango River has been a major target for alluvial diamonds which are and continue to be mined from its terraces, younger river flats and present-day river channel. The terraces have maximum ages of Early to Middle Pleistocene. Most of the diamonds have been recovered from large diamond placers in …

North America's Largest Alluvial Diamond Was Unearthed in West ia in 1928. In the tiny town of Peterstown at the southern tip of West ia, a weathered historical marker describes the remarkable find of William "Punch" Jones and his father Grover C. Jones Sr., who unearthed North America's largest alluvial diamond — a …

Alluvial mining for diamonds. Around 10 percent of the world's rough diamonds are sourced through industrial alluvial mining, while another 14 percent are uncovered using small-scale alluvial ...

The Jones Diamond is a blue-white alluvial diamond that was discovered in Peterstown, West ia, way back in 1928. It spent the Great Depression hiding inside a cigar box in a tool shed, until in 1942, Punch rediscovered his stone and took it to a geology professor at ia Tech.

The alluvial diamond fields of the North W est Province. extend over an area of some 25,000 km 2 The total. reported production from these diamond fields from.

alluvial: [adjective] relating to, composed of, or found in alluvium.

These alluvial diamonds are recovered by placer and marine mining techniques that are very different from hard-rock kimberlite mining. Although these specimens are found "off-craton," they derive from "on …

It demonstrated that this alluvial field is overall a low-volume, small-diamond and uneconomic placer, with higher diamond concentrations in localised areas. The low potential is attributed to the limited availability of diamonds from secondary detrital sources, coupled with the inefficiency of fluvial mechanisms to promote diamond concentration.

Abstract and Figures. Diamonds from alluvial deposits near Wellington, New South Wales, have been characterized on the basis of morphological features, mineral inclusions, C isotope signatures, N ...

While minor diamond discoveries were made among alluvial gold in New South Wales starting in 1851, a discovery in 1979 on the Kimberley Plateau of Western Australia enabled the country to be the world's most prolific diamond producer. Based on ancient bedrock, diamond exploration began in 1972, with a kimberlite pipe discovery coming in 1976 in ...

alluvial diamond resources. A similar assessment was also conducted by the U.S. Geological Survey (USGS) in Liberia (Wahl and others, 2007). The USGS assessment made sub-stantial contributions to the assessment process of the diamond potential and contributed to a lifting of the sanctions on mining and selling of diamonds imposed on …

The diamond in the Gbenko alluvial deposits in Guinea (West Africa), mined by Aredor Guinee S. A., have a gem content of 93%. At present these have an average carat price close to US300, probably ...

assess the geological resource potential and the rough diamond. production capacity in Ghana. The speci c goals of this project are as follows: 1. Acquire and provide remote sensing imagery of ...

This reading list was compiled to give you an opportunity to learn more about the history of alluvial diamonds from Namibia. A number of the articles were published …

Alluvial diamonds have been mined in most Brazilian states since the beginning of the 18th century, when the colony was still under Portuguese rule. Besides alluvial occurrences, there are other important deposits …

The extremely low concentrations of diamond in most alluvial deposits and the almost random distribution of the diamonds within the gravels, necessitate the taking of large samples in order...

Alluvial mining in the area started in the early 19 th century. Renewed interest in the mining of alluvial diamonds was generated by the El Niño related drought of 1974 when many farmers turned to diamond mining. Much larger volumes of gravel could be moved and greater depths of gravel were reached owing to modern earth moving and sorting ...

The diamond in the Gbenko alluvial deposits in Guinea (West Africa), mined by Aredor Guinee S. A., have a gem content of 93%. At present these have an average carat price close to US300, probably ...

Local News. The largest alluvial diamond in North America was found in Rich Creek near Peterstown, West ia. It's called the Jones Diamond, a blue-white gem weighing 34.46 carats, or 34.48 depending on the source, and measuring 5/8 inch in …

The Woyie River rough diamond weighed 770 carats and was dubbed one of the largest alluvial diamonds ever to be found. And the Sergio diamond (3167 carats), weighing slightly more than the Cullinan, is a carbonado diamond, a rare black diamond. And most recently we wrote about the Lulo Rose, a 170 carat pink diamond.

A strong case can be made for the Sibumasu diamonds being derived from an Australian/Gondwanan source as the alluvial diamonds are associated with Carboniferous–Permian diamictites and this combined with palaeomagnetic data indicate Sibumasu was part of Gondwana at the time (e.g. Metcalfe, 1996), with the diamonds …

The alluvial diamonds appear to have been sourced from the important northeastern Lesotho diamond field, which is the source of the bulk of diamond production in the Kingdom of Lesotho. The project has yet to be subjected to a systematic exploration and sampling programme. ExplorMine is currently actively seeking investment partners for …

Alluvial diamonds from Wellington, Bingara, Copeton, and Airly Mountain in New South Wales form two distinct groups, here termed A and B. Group A diamonds are similar to those found in kimberlites and lamproites globally and are thought to have formed in Precambrian lithospheric mantle. Group B diamonds have unusual characteristics …

Despite the importance of alluvial diamonds produced with respect to total diamond production in terms of their values, the alluvial deposits themselves have little to teach …

The earliest diamonds in South Africa were also alluvial, but later diamonds were found in their host rock, kimberlite. Finding the host rock meant that diamonds could be mined in higher concentrations and greater quantities than before. This made large-scale open-pit mining worthwhile, transforming how diamonds are unearthed.

The alluvial diamonds are in a coarser size fraction range, from 2.3 to 5.6 mm. They are comparable to Collier-4 diamonds regarding their resorption degree and occurrence of macles (15 %) and aggregates (10 %). A total of 58 % of alluvial diamonds are dodecahedra, and 15 % are octahedral diamonds.

The general principles that govern any search for alluvial diamonds, the processes involved in alluvial diamond deposition and the methods and technology used in exploring for and evaluating such deposits are also discussed. The principles are illustrated, where possible, by reference to a case history of exploration for alluvial …