Crystalline rock, any rock composed entirely of crystallized minerals without glassy matter. Intrusive igneous rocks—those that congeal at depth—are virtually always crystalline, whereas extrusive igneous rocks, or volcanic rocks, may be partly to entirely glassy.

2024年1月31日 · Igneous rocks are characterized by several distinct properties: Crystalline Texture: They often have a crystalline texture due to the interlocking of crystals that form as the molten rock cools. Hardness and Density: Most igneous rocks are hard and dense.

Igneous rock may form with crystallization to form granular, crystalline rocks, or without crystallization to form natural glasses. Igneous rocks occur in a wide range of geological settings: shields, platforms, orogens, basins, large igneous provinces, extended crust and oceanic crust.

Crystalline rock means any rock composed entirely of crystallized minerals without glassy matter. Intrusive igneous rocks are those that congeal at depth and are virtually always crystalline, whereas extrusive igneous rocks, or volcanic rocks, may be partly to entirely glassy.

2023年7月9日 · Igneous rocks are typically hard and dense, resistant to weathering, and often exhibit a crystalline structure. Intrusive rocks have larger crystals due to slower cooling, while extrusive rocks have smaller crystals resulting from rapid …

2025年1月25日 · igneous rock, any of various crystalline or glassy rocks formed by the cooling and solidification of molten earth material. Igneous rocks constitute one of the three principal classes of rocks, the others being metamorphic and sedimentary.

Igneous rocks derive from the solidification of magma or lava in crystals and, eventually, volcanic glass. When they crystallize from a melt, growing crystals compete for space and may get reabsorbed if their chemical composition is in disequilibrium with the surrounding melt.

Igneous rocks are common in the geologic record, but surprisingly, it is the intrusive rocks that are more common. Extrusive rocks, because of their small crystals and glass, are less durable. Plus, they are, by definition, exposed to the elements of erosion immediately.

2023年10月19日 · Igneous rocks form when magma (molten rock) cools and crystallizes, either at volcanoes on the surface of the Earth or while the melted rock is still inside the crust. All magma develops underground, in the lower crust or upper mantle, because of the intense heat there.

2025年2月11日 · The textures of igneous rock define their crystallinity, grain size, and crystal relations, reflecting their cooling history and formation conditions. Various types of textures of igneous rock: (A) Crystallinity: Defines the degree of crystallization. Holocrystalline: Rocks composed entirely of crystal. Example: Granite, Granodiorite. Hemi ...