Titanium-rich biotite from granodiorite belonging to redwitzite suite of the Slavkovský les Mts. alters to mixture of low-Al titanite, Mn-enriched ilmenite, REE-fluorocarbonate (parisite) and very fine-grained mixture of chlorite and clay minerals. Titanite consists from 1.1 to 2.3 wt. % Al2O3 and from 0.4 to 1.0 wt. % Fe2O3. Titanite shows some Al+Fe3+ excess over F with significant amount of (Al+Fe3+)-OH titanite component (4-9 mol. %). Ilmenite contains considerable amount of pyrophanite component (5-8 mol. %). The retrograde assemblage of titanite with considerable amount of (Al+Fe3+)-OH titanite component and presence of ilmenite, together with chlorite, argued for low-temperature breakdown of biotite in reducing conditions., Miloš René., and Obsahuje bibliografii