Etch channels in garnets from allivium of Syuzyu river (South Timan)

We found garnets, penetrated by numerous etch channels, in a stream-sediment sample from alluvium of the Syuzyu River (South Timan). We studied morphological features, internal structure and chemical composition of the garnet by a scanning electron microscope. We established that they were andradite-grossulars, typical for skarns, but with peculiar negative relief - etch channels and wedge-shaped depressions. Such forms, which are traditionally considered a typomorphic feature of pyropes of diamondiferous associations, were for the first time discovered in calcareous garnets. We assumed that the negative forms of relief was conditioned by epigenetic changes resulted from occurring of the mineral in the weathering crust.