... The effect is strongest in the most evolved, high-latitude supergiant V5112 Sgr=IRAS19500-1709, which has an extended structured envelope (Figs.1 and 2). In the optical spectrum of this object, the BaII ion lines are split into three components (Figs.3 and 4). ... Thus, we discovered for the first time the enrichment of the stellar envelope with heavy metals produced at the AGB stage. ... Detection of heavy-metal lines in the spectrum of the circumstellar envelope of a post-AGB star. ...