This granite pegmatite contains large sheets of muscovite mica, orthoclase feldspar and quartz matrix. An excellent teaching material which comes from Southern Norway. Each specimen comes in a labelled card tray.
Most pegmatites are similar in composition to granite containing quartz, feldspars & micas. The most striking features of this igneous rock are the large crystals, usually over 1" (2.5cm) in size. Some can even be metres across & demonstrate perfect textbook morphological examples. To attain this size the crystallisation mechanism would need to have been very protracted. Pegmatite bodies tend to be small & marginal to other igneous intrusives. Their mode of formation is uncertain but they could be derived from high temperature & pressure magmatic, metasomatic or metamorphic processes, or a combination