pegmatite

[ peg-muh-tahyt ]

noun

, Petrology.

1. a coarsely crystalline granite or other high-silica rock occurring in veins or dikes.

pegmatite

/ ˈpɛɡməˌtaɪt; ˌpɛɡməˈtɪtɪk /

noun

1. any of a class of exceptionally coarse-grained intrusive igneous rocks consisting chiefly of quartz and feldspar: often occurring as dykes among igneous rocks of finer grain

pegmatite

/ pĕg′mə-tīt′ /

1. Any of various coarse-grained igneous rocks that often occur as wide veins cutting across other types of rock. Pegmatites form from water-rich magmas or lavas that cool slowly, allowing the crystals to grow to large sizes. Although pegmatites can be compositionally similar to a number of rocks, they most often have the composition of granite.

Derived Forms

• pegmatitic, adjective

Other Words From

• peg·ma·tit·ic [peg-m, uh, -, tit, -ik], adjective

Word History and Origins

Origin of pegmatite¹

1825–35; < Greek pēgmat- (stem of pêgma ) anything fastened together, a bond (compare pēgnýein to stick) + -ite ¹

Word History and Origins

Origin of pegmatite¹

C19: from Greek pegma something joined together

Example Sentences

Primary sources for lithium like pegmatites and volcanic clays are well understood, but finding other stores that are safe and economical to exploit would be helpful.

From Science Daily

The pegmatites in the Spruce Pine Mineral District, an area about 25 miles long and 10 miles wide, were formed hundreds of millions of years ago under intense heat and pressure.

From Los Angeles Times

Some of the most visually striking – the emeralds, garnets, topazes and aquamarines that Busse seeks – are pegmatites that form when magma forces its way into underground cracks, then cools slowly.

From The Guardian

Piedmont Lithium says it would be the nation’s only hard-rock mine, extracting lithium from a mineral, spodumene, that is found in rock called pegmatite.

From Seattle Times

The resulting folds are easy to see, because molten pegmatite penetrated the voids.

From New York Times