THE POSSIBILITY OF A RADIATIVE AND CHEMICAL PROCESS OF THE FORMATION OF NANOMETRIC DIAMOND GRAINS IN METEORITES

The hypothesis of a radiative and chemical process of nanometric diamo nd-grain formation in meteorites does not take into account an importa nt aspect of the diamond origin problem i.e., the presence of isotopic ally anomalous components of a number of elements. Taking this fact in to consideration leads us to the hypothesis that diamond grains in cho ndrites consist of two populations. One of them is formed in situ in t he course of the radiative and chemical process, whereas the other one has a presolar origin. An experiment on diamond extraction from a car buranium sample gave a negative result, whereas according to the radia tive and chemical process hypothesis, at least 150 mg of diamond shoul d have formed in the sample. It is possible that the process is extrem ely inefficient and does not play an important part in diamond formati on in meteorites.