The Cap de Creus (NE Spain) is the easternmost outcrop of the Hercynian basement of the Pyrenees.
The peninsula is constituted by materials affected by the hercynian metamorphism. A pegmatitic field occurs within the metamorphic rocks in the northern part of the Cap de Creus peninsula. Four pegmatite types have been established according to internal structure and mineralogical criteria: microcline-rich (type I); beryl-columbite (type II); beryl-columbite phosphate (type III) and albite (type IV). The composition of moscovite and feldspars have been studied. The K/Rb ratio decreases progressively from type I to type IV, and also there is a progressive enrichment in P, Cs, and Y, according to the degree of pegmatite evolution