Impact diamonds of the Popigai astrobleme: Main properties and practical use

In the 1960s, the so-called schistose placer diamonds were found in sandy sediments of Ukraine. Their primary source remained unknown and their origin was supposed to be cosmic, by analogy with the diamonds detected in some meteorites. In the early 1970s, similar diamonds were found in terrestrial rocks of the Popigai impact crater (astrobleme) in northern Siberia. It was shown that these diamonds are products of the transformation of graphite contained in gneisses (Masaitis et al., 1972). Later, such diamonds were found in other astroblemes in Russia, Ukraine, Germany, Finland, and Canada. Impact diamonds markedly differ from diamonds hosted in kimberlites and lamproites in their appearance and in other features. In the 1970s-1990s, diamonds from the Popigai astrobleme were studied in many research institutions of Russia, Ukraine, and outside the USSR. The results of these investigations have been mostly published, and my brief review is based on these data.