About Diamonds of the Ingul-Ingulets Domain (the Ukrainian Shield)

Abstract

Three finds of diamonds on the Ingul-Ingulets domain of the Ukrainian Shield are considered: in breccia-like rocks of the Gruzke area, in eclogite-like rocks in the basin of the Ingul River and the Zeleny Gayi meteorite crater. A brief description of these diamonds is made, which represent their different geological and genetic types. Тhe veracity of these diamond findings and the origin of their crystals are appreciated. It is shown that 8 diamonds of the Gruzke area differ in size (0.2-1.4 mm), shape, colour, set of nitrogen centres and degree of preservation. According to infrared spectroscopy, all the studied crystals can be attributed to natural diamonds of the mantle type and distinguish them into separate groups, as they belong to several spectral types: IIa, IaAB, Iab and Ib. However, there are several doubts about the veracity of this finding: 1. Finding in small samples of the core wells of such a high concentration of diamonds. 2. A large variety of crystals in these samples by spectral types of physical classification. 3. Signs of mechanical wear on all crystals, which does not exclude the version of their origin from a diamond drill bit (a mixture of crystals of the natural and possibly synthetic diamond). The question of whether the found diamonds belong to the breccia-like rocks of the Gruzke area remains open. Small diamonds (up to 0.3 mm), which are found in eclogite-like rocks in the basin of the Ingul River on several grounds (mainly cubo-octahedral habit, manifestations of skeletal forms of growth, flat surface of the cube faces, yellow-green colour, inclusions) are very similar to crystals of synthetic HPHT diamond. However, the same small diamonds are found in the rocks of the Euro-Asian Alpine and the Ural and Central-Asian Caledonian ophiolite belts and the eruptions of modern volcanoes in Kamchatka. Such diamonds are also found in lamproite-like rocks of the Mriya pipe in the Azov Sea region, and they are found in weathering crusts and terrigenous deposits of Ukraine. It is necessary to find out the true nature of these findings. Therefore, it is necessary to audit all finds of such diamonds in Ukraine. It is shown that diamonds from the Zeleny Gayi meteorite crater are typical impact apographitic crystals - diamond paramorphoses on graphite. The conclusions of some researchers about the mantle nature of these diamonds from this crater are denied.