Any rock composed entirely of crystallized minerals without glassy matter (matter without visible crystals).
Intrusive igneous rocks (see intrusive rock ) are nearly always crystalline; extrusive igneous rocks (see extrusive rock ) may be partly to entirely glassy. Metamorphic rocks are also always completely crystalline and are termed crystalline schists or gneisses . Sedimentary rocks can also be crystalline, such as crystalline limestones that precipitate directly from solution; the term is not generally applied to clastic sediments (made of fragments of preexisting rock), even though they are formed largely from the accumulation of crystalline materials.