pegmatite

peg·ma·tite  (pgm-tt)

n.

A coarse-grained granite, sometimes rich in rare elements such as uranium, tungsten, and tantalum.

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[Greek pgma, pgmat-, something fastened together (from pgnunai, to fasten; see pag- in Indo-European roots) + -ite.]

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pegma·titic (-ttk) adj.

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pegmatite [ˈpɛgməˌtaɪt]

n

(Earth Sciences / Geological Science) 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

[from Greek pegma something joined together]

pegmatitic  [ˌpɛgməˈtɪtɪk] adj

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pegmatite  (pgm-tt)

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.

Thesaurus

Noun

1.

pegmatite - a form of igneous rock consisting of extremely coarse granite resulting from the crystallization of magma rich in rare elements igneous rock - rock formed by the solidification of molten magma samarskite - a complex black mineral occurring in pegmatites