For the first time, an unusual assemblage of talc-phengite-chlorite-K-feldspar was found in quartz schists from the Sanandaj-Sirjan zone in the Nahavand area in western Iran. The talc-bearing quartz schists occur as small bodies or lenses within pelitic schist layers and contain talc, phengite, chlorite, K-feldspar and quartz as major mineral constituents with subordinate amounts of calcite and graphite. Textural analysis revealed that talc, phengite, chlorite and K-feldspar are in sharp contact and no reaction rims between them were observed. Constructed petrogenetic gird in the K2O-FeO-MgO-Al2O3-SiO2-H2O (KFMASH) model system containing talc, phengite, chlorite, K-feldspar, phlogopite and kyanite with excess quartz and H2O shows that divariant assemblage of talcphengite-chlorite-K-feldspar is stable over a wide P-T range defined by the following two univariant reactions: phengite+talc+quartz=chlorite+K-feldspar+kyanite+H2O and chlorite+phlogopite+quartz=talc+ phengite+K-feldspar+H2O. Constructed Al2O3-KAlO2-MgO+FeO (AKM) compatibility diagrams predict that phengite (XPh=0.280, YPh=0.860), chlorite (XChl=0.570, YChl=0.640), talc (XTlc=0.160, YTlc=0.02) and Kfeldspar are stable at P=11 kbar and T=400oC. This relatively high-pressure assemblage could be formed during the subduction of the Neo-Tethys oceanic plate under Iranian microcontinent.