A pegmatite is a holocrystalline, intrusive igneous rock composed of interlocking phaneritic crystals usually larger than 2.5 cm in size (1 inch). source
A pegmatite is a holocrystalline, intrusive igneous rock composed of interlocking phaneritic crystals usually larger than 2.5 cm in size (1 inch).
The word pegmatite derives from Homeric Greek, which means “to bind together” . source
The word pegmatite derives from Homeric Greek, which means “to bind together” .
Most pegmatites are composed of quartz, feldspar and mica, having a similar silicic composition as granite. source
Most pegmatites are composed of quartz, feldspar and mica, having a similar silicic composition as granite.
Mafic pegmatites containing amphibole, Ca-plagioclase feldspar, pyroxene. source
Mafic pegmatites containing amphibole, Ca-plagioclase feldspar, pyroxene.
Crystal size is the most striking feature of pegmatites, with crystals usually over 5 cm in size. source
Crystal size is the most striking feature of pegmatites, with crystals usually over 5 cm in size.
Individual crystals over 10 metres (33 ft) long have been found, and many of the world's largest crystals were found within pegmatites. source
Individual crystals over 10 metres (33 ft) long have been found, and many of the world's largest crystals were found within pegmatites.
Similarly, crystal texture and form within pegmatitic rock may be taken to extreme size and perfection. source
Similarly, crystal texture and form within pegmatitic rock may be taken to extreme size and perfection.
Feldspar within a pegmatite may display exaggerated and perfect twinning, exsolution lamellae. source
Feldspar within a pegmatite may display exaggerated and perfect twinning, exsolution lamellae.
Perthite feldspar within a pegmatite often shows gigantic perthitic texture visible to the naked eye. source
Perthite feldspar within a pegmatite often shows gigantic perthitic texture visible to the naked eye.
Crystal growth rates in pegmatite must be very slow to allow gigantic crystals to grow within the confines and pressures of the Earth's crust. source
Crystal growth rates in pegmatite must be very slow to allow gigantic crystals to grow within the confines and pressures of the Earth's crust.
Pegmatite is difficult to sample representatively due to the large size of the constituent mineral crystals. source
Pegmatite is difficult to sample representatively due to the large size of the constituent mineral crystals.
Syenite pegmatites are quartz depleted and contain large feldspathoid crystals instead. source
Syenite pegmatites are quartz depleted and contain large feldspathoid crystals instead.
Pegmatites are important because they often contain rare earth minerals. source
Pegmatites are important because they often contain rare earth minerals.
Worldwide, notable pegmatite occurrences are within the major cratons, and within greenschist-facies metamorphic belts. source
Worldwide, notable pegmatite occurrences are within the major cratons, and within greenschist-facies metamorphic belts.
pegmatite localities are only well recorded when economic mineralisation is found. source
pegmatite localities are only well recorded when economic mineralisation is found.
Pegmatites can be classified according to the elements or mineral of interest, for instance "lithian pegmatite" to describe a Li-bearing. source
Pegmatites can be classified according to the elements or mineral of interest, for instance "lithian pegmatite" to describe a Li-bearing.
