The heavy mineral assemblages of the Brkini Flysch Basin (Western Slovenia) have been studied in some detail, and new minerals, hitherto not mentioned in the literature have been found. Among these, Cr-spinels, ilmenites and one orthopyroxene were recognized. All of them were chemically characterized. Chemical analyses on garnets have been carried out in order to discriminate between different end-members and they turned out to be similar to those found in both the Julian (Slovenian) and Istrian basins located to the NW and SE of Brkini, respectively. The chemistry of Cr-spinels suggests that both peridotitic (type-II and minor type-I peridotites Cr-spinels) and volcanic spinels are present. This fact suggests that the Outer Dinarides of former Yugoslavia, where type-I peridotites are present, began to be eroded by Middle Eocene. Moreover, similarities between the minerals of Brkini and those of the Julian and Istrian basins show that supplies from both the NW and the SE areas are present.