What is an aplite in geology ?

Aplite : definition

The aplite is a granite rock with very fine grains (infra-millimeter crystals), of light color, composed of quartz, albite, orthoclase, oligoclase, microcline, muscovite and tourmaline.

The aplite is generally presented in veins intersecting the granite massifs (photo on the right), frequently associated with pegmatite veins of which it can constitute the borders. Aplites and pegmatites represent the last "juices" of crystallization of the magma in which a whole procession of so-called "incompatible" rare elements are concentrated (B, Be, Nb, Ta, etc...).