peg·ma·tite /ˈpɛgməˌtaɪt/
  偉晶岩
  Peg·ma·tite n.  Min. (a) Graphic granite. See under Granite. (b) More generally, a coarse granite occurring as vein material in other rocks.
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  pegmatite
       n : a form of igneous rock consisting of extremely coarse
           granite resulting from the crystallization of magma rich
           in rare elements