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In geology, solid-state recrystallization is a metamorphic process that occurs under high temperatures and pressures where atoms of minerals are reorganized by diffusion and/or dislocation glide. During this process, the physical structure of the minerals is altered while the composition remains unchanged.
Sedimentary rocks are formed through the gradual accumulation of sediments: for example, sand on a beach or mud on a river bed. As the sediments are buried they get compacted as more and more material is deposited on top. Eventually the sediments will become so dense that they would essentially form a rock. This process is known as lithification.
Euhedral (also known as idiomorphic or automorphic) crystals are those that are well-formed, with sharp, easily recognised faces. The opposite is anhedral (also known as xenomorphic or allotriomorphic ), which describes rock with a microstructure composed of mineral grains that have no well-formed crystal faces or cross-section shape in thin ...
Deformations are numbered according to their order of formation with the letter D denoting a deformation event. For example, D 1, D 2, D 3. Folds and foliations, because they are formed by deformation events, should correlate with these events. For example, an F 2 fold, with an S 2 axial plane foliation would be the result of a D 2 deformation.
The types and abundance of minerals in a rock are determined by the manner in which it was formed. Most rocks contain silicate minerals, compounds that include silica tetrahedra in their crystal lattice, and account for about one-third of all known mineral species and about 95% of the earth's crust. [6] The proportion of silica in rocks and ...
Cumulate rock – Igneous rocks formed by the accumulation of crystals from a magma either by settling or floating. Flow banding – Bands or layers that can sometimes be seen in rock that formed from magma; Fractional crystallization (chemistry) – Method for refining substances based on differences in their solubility
A rock may consist of one type of mineral or may be an aggregate of two or more different types of minerals, spacially segregated into distinct phases. Some natural solid substances without a definite crystalline structure, such as opal or obsidian, are more properly called mineraloids. If a chemical compound occurs naturally with different ...
Some form of recovery process, such as dislocation climb or grain-boundary migration must also be active. Slipping of the dislocation results in a more stable state for the crystal as the pre-existing imperfection is removed. It requires much lower differential stress than that required for brittle fracturing. This mechanism does not damage the ...