pegmatitischer

Pegmatitischer is a German adjective meaning "pegmatitic." It describes rocks that are pegmatites. Pegmatites are exceptionally coarse-grained igneous rocks. They form from the last dregs of magma or lava to crystallize, which are typically enriched in incompatible elements and volatiles. These late-stage melts are often depleted in the more common rock-forming minerals, leading to the crystallization of larger crystals of minerals that may be less common in other igneous rocks. The slow cooling rate of these large intrusions allows for significant crystal growth.

Pegmatites are characterized by their extremely large crystal sizes, often measuring several centimeters to meters in length. Common minerals found in pegmatites include feldspar, quartz, mica, and tourmaline, but they can also host a wide variety of rare minerals due to the enrichment of trace elements in the parental melt. These rare minerals can include lithium-bearing minerals, rare earth element minerals, and gemstones.

The geological setting for pegmatite formation is typically associated with large igneous intrusions, such as granite batholiths. They can occur as dikes, sills, or irregular bodies within or surrounding these larger igneous bodies. Pegmatites are of significant economic interest because they are often a primary source of lithium, beryllium, tantalum, niobium, and gemstones like tourmaline, aquamarine, and kunzite. Their unusual mineralogy and large crystal sizes make them a subject of study for geologists interested in magmatic processes and the formation of rare mineral deposits.