Kimberlite diamond

Diamond is crystallized in cubic form (O ) with tetrahedral coordination of C-C bonds around each carbon atom. The mononuclear nature of the diamond crystal lattice combined with its high symmetry determines the simplicity of the vibrational spectrum. Diamond does not have IR active vibrations, while its Raman spectrum is characterized by one fundamental vibration at 1,332 cm . It was found that in kimberlite diamonds of gem quality this Raman band is very strong and narrow, hi defect varieties the spectral position does not change, but the band is slightly broader (Reshetnyak and Ezerskii 1990). 

Natural diamonds are found in kimberlite of ancient volcanic "pipes," found in South Africa, Arkansas, and elsewhere. Diamonds are now also being recovered from the ocean floor off the Cape of Good Hope. About 30% of all industrial diamonds used in the U.S. are now made synthetically. 

Diamonds are found in ancient volcanic pipes embedded in a relatively soft, dark coloured basic rock called blue ground or kimberlite , from the South African town of Kimberley where such pipes were first discovered in 1870. Diamonds... 

A. Dissemination Disseminated crystallisation without concentration Most diamond bearing kimberlite pipes... 

Keywords diamond, kimberlite, soil geochemistry, imaging, volatile... 

Results of the Edehzhie survey (a hybrid survey) have been used to adjust suggested protected area boundaries and make compromises in light of mineral potential. There is a high kimberlite potential on the Horne Plateau, as suggested by the presence of indicator minerals and a small diamond recovered from a bulk stream sediment sample (Day et al., 2007). 

Potential for diamond-bearing kimberlites is also present Sambaa K e area. There are basement and structural similarities with the Buffalo Head Hills kimberlite field, Alberta (Prior et al. 2007) and there is ongoing diamond exploration within the WCSB to the north as well. Further discussion has altered the potential boundaries for the proposed protected area on the Horn Plateau and discussions are ongoing before any permanent decisions are made by all parties involved. Analytical results for the remaining two areas are pending. 

Abstract Chronological studies of kimberlite-host rocks in the diamondiferous Buffalo Head Hills kimberlite field of north-central Alberta facilitate new interpretation of the nature, timing and sequence of kimberlite eruptions in northern Alberta. Three different emplacement episodes are recognized in association with volcanic and intrusive activity Late Cretaceous ( 88-81 Ma) Smoky Group equivalent intra- and extra-crater facies, Late Cretaceous and Paleocene ( 81 and 64 Ma) intrusion of sills or dykes, and Paleocene ( 60 Ma) Paskapoo Formation equivalent intra-crater facies. These specific periods of magmatism correspond to characteristic intra-field features such as spatial distribution, rock classification and diamond content. 

The importance of defining settings for Late Cretaceous volcanic activity in this region is emphasised by new geochronological data that show the two kimberlites with the highest diamond estimates to date, K14 and K252, are included in a 14-point Rb-Sr phlogopite isochron age of 81.5 0.8 Ma... 

Selandian Rb-Sr ages of 59.6 2.8 Ma and 60.3 0.8 Ma were determined for the K1A and K19 bodies, respectively these bodies occur in the southwestern part of the field and are either barren of diamond or have the poorest diamond results within this field (Hood McCandless 2004 Fig 1). Mineralogical (e.g., amphibole, sanidine) and geochemical evidence (e.g., flatter chondrite-normalized REE pattern versus the steep profile of typical kimberlite) enticed Eccles et al. (2008) to conclude that these rocks are better referred to as hybrid kimberlite-ultrabasic rocks. 

Because of their proximity ( 770 km) and similar Class 2 kimberlite designation, some discussion of the similarities and dissimilarities between the Buffalo Head Hills and Fort a la Come fields is warranted. Both fields are dominated by primary pyroclastic, volcaniclastic and resedimented volcaniclastic kimberlite, and have large, multi-aged bodies. Hence, a favourable consequence to diamond explorers is that the inter- and extra-crater morphologies of Class 2 kimberlite in the WCSB could cover vast areas. 

Sulfur occurs in a variety of forms in the mantle, the major sulfur phase is monosulfide solid solution between Fe, Ni, and Cu. Recent ion microprobe measurements on sulfide inclusions from megacrysts and pyroxenite xenohths from alkali basalts and kimberlites and in diamonds gave 5 " S-values from — 11 to - - 14%c (Chaussidon et al. 1987, 1989 Eldridge et al. 1991). Sulfur isotope variations within diamonds exhibit the same characteristics as previously described for carbon i.e., eclogitic diamonds are much more variable than peridotitic diamonds. 

Figure 9.7. Statistics on diamond morphologies associated with different kimberlite pipes in Siberia. The areas with vertical lines represent an octahedral morphology with only a slight dissolution those with the circles show crystals bounded by curved faces, which received heavier dissolution. Blank areas correspond to an intermediate type.

Recently, diamond synthesis has been successfully performed under high-temperature, high-pressure conditions in a system using kimberlite powder, various carbonates, sulphates or water as the solvent [13], [14]. Higher pressure and temperature conditions are required in a non-metallic solution than in a metallic solution, and the crystals obtained are mainly simple octahedral, differing from those observed in crystals grown from metallic solutions. Crystals synthesized in a non-metallic solution show the same characteristics as natural diamond Tracht. These observations indicate that the solvent components have a definitive effect upon surface reconstruction, and thus on the morphology of the crystals. 

Many of the diamonds in t)q)es (2) and (3) were trapped in the uplifting process of kimberlite and lamproite magma and were brought up to the Earth s surface, whereas it is thought that those in t5q>e (1) have been brought up by a reverse sub-duction movement. 

M. Arima, Experimental study of growth and resorption of diamond in kimberlitic melts at high pressures and temperatures, in Advanced Materials 96,Tsukuba, NIRIM,... 

Diamonds were found originally as loose erysials in geologically undent alluvial stream beds. Later, their host formations were found to be a basic igneous rock [kimberlite) in the Republic of South Africa Diamonds are the products of extremely high-temperature, high-pressure env ironment and tire composed of pure carbon See also Diamond. 

Kimberlite from which diamonds are secured is commonly called a mica peridotite blit is more closely related to the lamprophyres. See also Kimberlite. 

Diamonds are formed under intense pressure and heat. It is found in the igneous rock and gravel, but is unevenly distributed. South Africa and Russia are the largest producers of diamond. The diamond mines at Kimberly in South Africa are famous. In fact, the diamond bearing rock is called Kimberlite. 

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