Isotopic compositon of carbon in polycrystalline aggregates of diamond with inclusons of garnet and rutile from the Mir pipe

Polycrystalline aggregates of bort-type diamond with inclusions of garnet a nd rutile from the Mir pipe have delta C-13 of -3.7 to -22.9 parts per thou sand PDB. The bort of variety VIII (Yu.L. Orlov's classification) differs f rom the bort of variety IX in having a narrower range of delta C-13 (-3.7 t o -9.4 and -3.8 to -22.9 parts per thousand, respectively). The isotopicall y heavy diamond aggregates (delta C-13>similar to 10 parts per thousand) wi th cubic individuals make the maximum contribution of C-12 as compared with the aggregates having individuals of other morphological types. Within the Mir pipe, the E-type bort is statistically enriched in C-13 relative to si ngle diamond crystals of the same paragenesis.