Pumpellyite has been found for the first time in phyllites and synfolial veins in Permo-Triassic formations in the Beni Mezala 1 unit, part of the Federico units, Internal Zone of the Rif belt, Spain. Back-scattered images indicate that equilibrium was attained only at the millimeter scale or lower. Two main assemblages were identified in different microdomains: 1) pumpellyite - actinolite - epidote and 2) pumpellyite - muscovite - epidote. Only the second assemblage was identified in phyllites. Chlorite rarely occurs in these rocks, whereas vermiculite is abundant. Epidote is Fe-rich; actinolite contains very low Na and Al, and white mica has a mean Si content of 3.13 atoms per formula unit, all these characteristics being typical of low-pressure conditions. Assemblages in pumpellyite-bearing rocks indicate pressures of similar to 2 kbar and temperatures of similar to 250 degrees C, in agreement with the estimates deduced from crystal-chemical parameters of white mica and chlorite from the enclosing pumpellyite-free phyllites. Nevertheless, peak conditions reached ca.400 degrees C and 5 kbar, as indicated by kyanite-bearing veins from the same area. Two compositionally different populations of pumpellyite occur: (i) a Fe-rich population, coexisting with actinolite, and (ii) an Al-rich population, present in actinolite-free rocks or microdomains. The mineral assemblages and phase compositions were thus mainly controlled by both reaction kinetics and microdomainal variations in composition.