ИСТИНА

Metamorphic diamond microcrystals are known from Kazakhstan and China [Xu et al,1992]. We also encountered them in residues of the thermochemical dissolution of garnet-biotite gneisses from Western Gneiss Region of Norway [Dobrzhinetskaya et al,1993]. They are very small (0,02-0,08mm) and have unusual forms. We investigated different crystals and proposed their morphological classification. The comparison of metamorphic crystals morphology with that of diamonds from kimberlites shows, that they are very much different. However, some forms of metamorphic crystals are similar to artificial diamonds. The similarity between metamorphic and synthetic diamonds permits us to apply the growth theory to explanation of the peculiarities of metamorphic diamond morphology. We suggest, that the in metamorphic rocks crystallized very quickly during a short time at non-equilibrium conditions at the low temperature and pressure from the supersaturated solutions which were rich in impurities.