Introduction
Pegmatites are suppliers of critical raw materials like beryllium, lithium and tantalum. Pegmatites also represent an important source of gemstones such as emerald and tourmaline, and some are even mined for their large, clean crys tals of quartz and feldspar. Pegmatites are abundant in Greenland, but few have been described or studied in detail and hence their economic potential is still little known at present.
In a broader sense, the term pegmatite is used for any coarse-grained vein of granitic composition, with or without a connection to an intrusive complex. Medium- to coarse-grained granitic to pegmatitic veins may be derived from partial melting of their host rocks during progressive high-grade meta morphism. Such veins are also termed migmatitic veins.
Mineralogically, pegmatites are termed simple when they essentially consist of quartz, feldspar and biotite, and complex when they carry a range of
accessory minerals like tourmaline, fluorite, lepidolite, spodumene or beryl. Also molybdenite, scheelite, uraninite and rare earth element-bearing miner als may occur in complex pegmatites.