Source: sciencedirect.com
Abstract
It is generally believed that the first diamonds ever found in Africa were discovered in South Africa in 1867. Actually, three diamonds had already been found in 1833 near Constantine (Algeria). One of these, still preserved, shows radiohalos that suggest an old age. It could be a Sahara diamond reworked in more recent sediments, possibly the Oligo-Miocene Numidian Flysch; however, this occurrence remains uncertain. The ancient Arabs or Berbers also knew of diamonds in the Reggane region (Algerian Sahara), at Bilād al-mās (
: “country of the diamond”). Since 1975, some 1500 diamonds have been collected from the alluvial deposits of this area. A manuscript written in Arabic in 1851 mentions diamonds in this region and describes their source rock, looked for in vain by modern geologists. The description is unclear, but might refer to Devonian oolitic ironstones. Modern investigations would rather suggest a kimberlitic primary source with intermediate Early Cretaceous palaeoplacers.
1. Introduction
Until the 18th century, India was the only known source of diamond. However, a few antique chronicles recounted that diamond also existed in northern Africa. Pliny, in particular, says in his Naturalis Historia (37.55) that the diamond existed in Ethiopia – that is, to the South of Egypt. It has also been reported that the Carthaginians exchanged precious stones, among which were diamonds, with the interior of Africa (e.g., Agricola, 1546, Heeren, 1799).
More recently, in 1834, the “Muséum national d’histoire naturelle”, Paris, purchased a diamond reportedly found in the Ghoumel River, near Constantine (Algeria). In addition, the papers of Du Couret’s Saharan mission (1849–1852) include an Arabic manuscript that describes diamonds in the Reggane region, which were rediscovered by modern exploration as late as 1975. Although it is frequently asserted that the first diamonds ever found on the African continent were discovered in South Africa in 1867, it seems that the Arabs and/or Berbers knew of diamonds in Algeria well before the colonial era.
A historical investigation of the Algerian diamonds, interesting in itself, also carries some geological interest. It may clarify the still enigmatic origin of the diamonds from Constantine and can provide indications in the quest for the source rock of the Sahara diamonds, for which modern geologists have searched for decades. Here, we relate the history of the diamond discoveries near Constantine and then in the Algerian Sahara, and recall forgotten historical information that may be useful for the knowledge and exploration of these deposits.
2. The Constantine diamonds
2.1. History of the finds
Saint Augustine, born in 354 AD in Thagaste (now Souk Ahras) at 125 km from Constantine (Fig. 1a) and bishop of Hippo (now Annaba, 120 km northeast of Constantine), evokes diamonds in his De Civitate Dei (21.4), but specifies neither their origin nor where he observed them. The first mention of a diamond from Constantine dates back to the 18th century; Magalotti, 1721, Magalotti, 1741 reports that a merchant from Constantine brought to Livorno in Tuscany a cut and engraved diamond of the “half size of a hazelnut”.
Fig. 1. (Colour online.) Diamond in Algeria: a: diamond finds; b: map of the Reggane region (dashed line: ancient caravan route between Akabli and Ouallen).
Later, in 1833, Paolo Francesco Peloso [1793–1856], consul of Piedmont-Sardinia at Algiers, sold to the French three diamonds reportedly found by a “native” in the auriferous gravels of the Ghoumel River, near Constantine. Two of these diamonds were shown in Algiers in November 1833 at an exhibition of the natural resources of Algeria (Guyon, 1834). In 1834, a French officer named Louis-Charles-Albert Sayde de Bellecôte [1807–1872] negotiated the sale of these diamonds to three mineralogical collections in Paris, namely “École des mines”, “Muséum national d’histoire naturelle” [MNHN] and Étienne de Drée’s private collection (Anonymous, 1835a). The discovery was presented at the “Société géologique de France” (Dufrénoy, 1834) and the “Académie des sciences” (Élie de Beaumont, 1838, Héricart de Thury, 1840; Table 1). Several American and European periodicals of the time echoed the find (e.g., Anonymous, 1835a, Anonymous, 1835b, Anonymous, 1835c, d’Avezac de Castera-Macaya, 1835–1836, Dureau de La Malle, 1837; see Boutan, 1886), which they presented as the first discovery of diamond ever made in Africa – the South African diamonds were discovered later, in 1867.
The geologists who worked in Algeria during the 19th century were embarrassed about this find, which they considered as a hoax and thus soon forgot. The geology of the Constantine province, which consists mostly of Mesozoic marine sediments hardly favourable to the presence of diamond, as well as the lack of new discoveries, discredited the find. It must also be recalled that, in the middle of the 19th century, diamond was known to occur only in India, Borneo and Brazil. Émilien Renou (1848) thought that the so-called Algerian diamonds may have come from the “pays de Bornou” (i.e., Chad region). In 1849, Henri Fournel, a leader of the Saint-Simonian movement, proposed a strange origin for these diamonds; in his Richesse minérale de l’Algérie, he imagines that they could have belonged to one of the adulterous women who, according to an ancient tale, were thrown into the Ghoumel gorge at Constantine during Roman times (Fournel, 1849–1854). As for the geologists who studied the Constantine region after Fournel, they simply ignored the diamonds (e.g., Coquand, 1854, Joleaud, 1912, Ville, 1869). The mineral catalogue of Algeria published in 1873 by Alexandre Papier does not mention them. It looks like an oversight; however, Papier certainly knew Bellecôte, who in 1834 had negotiated the sale of the diamonds in Paris, since they both lived in Bône (now Annaba) and were both members of the Académie d’Hippone. It seems that Papier (1873) deliberately ignored the Constantine diamonds.
Fournel’s hypothesis is indeed absurd, as the Romans were certainly not stupid enough to throw jewels away with their victims, but a hoax remains nevertheless possible. When the French entered the Kasbah of Algiers on 5 July 1830, they seized the treasury of the Dey of Algiers, Hussein Pasha. Soon afterwards, because of the French revolution of July 1830 and the subsequent abdication of King Charles X, the chiefs of the expedition were forced to leave Algiers and fled into exile. When the new French regime sent its own administrators to Algiers, most of the gold, silver and precious stones of the treasury had disappeared (Péan, 2004). A commission of inquiry noted that a few French had entrusted their spoils to the care of the consuls of England, Denmark and Piedmont-Sardinia, protected by diplomatic immunity (Flandin, 1835, p. 27). Did Bellecôte and the consul Peloso conceive an ingenious stratagem to sell three diamonds that, in reality, had been extracted from the Kasbah treasury? It is possible, but not proven. Bellecôte did not participate to the capture of Algiers in 1830, since he landed with the “4e Régiment de ligne” 2 years later. Moreover, the diamond still preserved at MNHN is less than one carat in weight, uncut and it is obviously not a jewel, so the hoax is not evident.
In the 1970s, Miocene lamproites were discovered in the Constantine province (Kaminsky et al., 1993, Raoult and Velde, 1971, Vila et al., 1974), reviving the interest for the Constantine diamonds meanwhile forgotten. Although new diamonds have not been found since 1833, this discovery provides a possible primary source for the Constantine diamonds.
2.2. Mineralogical observations
The three diamonds reportedly found at Constantine were purchased in 1834 for the “École des mines”, De Drée and MNHN mineralogical collections. There is apparently no mention of a diamond from Constantine at the “École des mines”; it could be one of the 23 diamonds of “unknown origin” that exist in the collection. De Drée’s collection was sold to the MNHN in 1844 (“Archives nationales” [AN]: AJ/15/545). Only one diamond from Constantine is still preserved at the MNHN (Fig. 2). Labelled “MIN000-5608”, it is recorded in the collection catalogue as found in the “Constantine Basin” and sold in 1834 by Bellecôte for 100 Francs. Alfred Lacroix (1893–1913, vol. 2, p. 354) described it as a “greenish octahedron, with curved faces, weighting 91 milligrams”, which does not match the weight of “11/4 karat” (i.e., ca 250 mg) mentioned for the same diamond by Héricart de Thury (1840) (Table 1).
Fig. 2. (Colour online.) The diamond from Constantine preserved at the “Muséum national d’histoire naturelle” in Paris. Macroscopic view (below) and secondary electron image (above); note the striations, the rounded edges and the left-bottom broken apex.
3. The Sahara diamonds
History of the finds
In 1849, the French adventurer Louis Du Couret [1812–1867?], also called Hadji Abd-El-Hamid Bey—he claimed to have converted to Islam—, initiated an expedition across Africa, from Tunis to Cap town (sic), for which he received instructions from the “Académie des sciences” (Élie de Beaumont, 1849). The mission actually ended in January 1852 at Touggourt, to the North of the Algerian Sahara, after an order of the French “Ministre de l’Instruction publique” (Anonymous, 1851, Du Couret, 1853). Du Couret brought back from Touggourt countless samples, maps and manuscripts that are still preserved (see Note 1 in Appendix A; Mantran, 1955). Soon afterwards, in 1854, Alexandre Dumas edited a fanciful version of Du Couret’s earlier journeys across equatorial Africa, in search of the so-called tailed men of the Niam-Niam tribe (Du Couret, 1854). This hoax discredited Du Couret, so the French “Académie des sciences” did not publish the results of his last mission to Touggourt and the MNHN accepted his samples with much reluctance (AN: AJ/15/545). Du Couret got a bad reputation of amateurishness if not of charlatanism (Emerit, 1956, Hill, 1955) and, after various cases against the French government (AN: 243AP/1) and Alexandre Dumas (BNF: Ms NAF 18918), both accused of not having complied with their commitments, his life ended miserably (AN: F/18/273; Hill, 1955).
Du Couret might have been an amateur, but he brought back from the Algerian Sahara various samples, unedited maps and original manuscripts. While he was at Touggourt, he collected information on the geology of Sahara from erudite persons of this region. In particular, Cid-El-Hadj-Abd-El-Kader Ben-Abou-Bekr-Et-Touaty (thereafter named Et-Touaty), born near Aoulef (Fig. 1b), wrote for him in Arabic a manuscript that describes the precious stones of the Sahara, among which are “emeralds” and “diamonds” (see Note 2 in Appendix A; Bargès, 1853). Et-Touaty wrote the following about diamond:
“As for the diamond, we have found it in our country [i.e., in the Aoulef region, near Akabli?], in the middle of black stones. Since we had no tools to break it, we left it in place. It resembled the grains of pomegranate, in the middle of this darkish mass, reflecting a shiny colour, like Pharaoh’s glass, grading from white to yellow. As for the place, we have found the stone between Ouallen and Akabli”.
4. Conclusion
Although the early finds of diamonds at Constantine (1833) and in the Sahara between Akabli and Ouallen by Et-Touaty (ca 1851) are debatable, it can be concluded that the ancient Arabs and/or Berbers knew some of the Algerian diamond occurrences, which were probably the first ever found in Africa in historical times, before the discoveries in South Africa in 1867 (see Boutan, 1886). This is undoubtedly testified to by the Arabic name Bled-el-Mass (i.e., “Country of the diamond”), given in ancient time to a region situated to the west of Akabli in the Reggane region and where diamonds have actually been found. However, like the emerald of the Garamantes, the diamond issue in ancient Algeria is difficult to sort out, since it consists of an inextricable mixture of false and true information, of myth and reality, of imaginary and real diamonds.
The scarce information and samples that are related to these early finds can contribute to unravelling the origin of the diamonds. The Constantine diamonds might have a Saharan origin through an intermediate palaeoplacer, but this occurrence remains uncertain. As for the diamonds of the Reggane region, modern investigations have favoured Jurassic kimberlites that are yet be found in the West African Craton, as a primary source, and the Early Cretaceous cover as a secondary source. Et-Touaty’s manuscript insinuates that the ancient Arabs or Berbers knew the source rock, which has been sought in vain for decades by modern geologists, and calls our attention to other possible sources. The diamondiferous “black stone harder than iron” briefly described by Et-Touaty can hardly refer to lamproites, unknown in this region, but it may depict Devonian oolitic ironstones, which deserve some attention, although not considered as a potential diamond placer till now. Finally, the regular concentric radiohalos observed at the surface of the Bled-el-Mass and Constantine diamonds should be considered carefully, as they could lead to the recognition of the intermediate sedimentary source.
There remains some chance to get more information on the diamond occurrences of the Reggane region, by assessing the ancient manuscripts that are preserved in the Touat khizanat. The Touat is an archipelago of oases that stretches on ca 150 km to the north of Reggane (Fig. 1b). It has been an important centre of civilization and still preserves numerous Arabic manuscripts (Bouterfa, 2005). Although most of these are devoted to religious or historical matters, a few of them deal with science. Their inventory, which has been initiated a few years ago and is still in progress (Bouterfa, 2005), might provide further information on how and where the diamonds were found by the Berbers and Arabs in the Reggane region.
