PLACER DIAMONDS OF THE EASTERN AZOV REGION

Abstract

The crystal morphology, photoluminescence behavior, nitrogen impurity concentrations and Raman spectra of diamonds from Quaternary alluvial deposits of the Eastern Azov region were studied. Macrodiamond from the Mius-Krynka river basin shown ideal rhombic dodecahedron habitus, and their geometric parameters are similar to those of rounded diamonds found in kimberlites and lamproites. The mantle temperature regime for the formation of Azovian diamonds was determined using infrared spectroscopy, the content and state of nitrogen impurities, and other defects in the crystals. Diamonds can be divided into different spectral types namely IaA, IaAB and IIa. They have low nitrogen contents from 19 to 491 ppm, with an average nitrogen content of 148 ppm and they have a relatively high degree of nitrogen aggregation (average value of % B = 33). Thermometric data for the Eastern Azov diamonds are in the range of 1097-1175 ºC for 2 billion years and 1120-1165 ºС for 3 billion years of crystals to stay in the mantle. N3, S1 and 575 nm centers are revealed in the photoluminescence spectroscopic measurements. The Raman shift for diamonds is in the range of 1331.0-1332.1 cm–1. The diamonds are probably associated with mantle eclogites, and they have been brought to Earth’s surface by kimberlites.