GRAPHIC PEGMATITE SPECIMEN
This is the polished on the one side graphic pegmatite specimen. Dimensions: 3.1 x 2.4 x 0.3″ (8 x 6 x 0.7cm). Weight – 2.3oz (66 grams). Origin: Russia, Transbaikalia.
Some information about pegmatite:
A pegmatite is a holocrystalline, intrusive igneous rock composed of interlocking phaneritic crystals usually larger than 2.5 cm in size (1 inch); such rocks are referred to as pegmatitic.
The word pegmatite derives from Homeric Greek pegnymi, which means “to bind together”, in reference to the intertwined crystals of quartz and feldspar in the texture known as graphic granite.
Most pegmatites are composed of quartz, feldspar and mica, having a similar silicic composition as granite. Rarer intermediate composition and mafic pegmatites containing amphibole, Ca-plagioclase feldspar, pyroxene, feldspathoids and other unusual minerals are known, found in recrystallised zones and apophyses associated with large layered intrusions.