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Basal, pinacoidal, or planar cleavage occurs when there is only one cleavage plane. Talc has basal cleavage. Mica (like muscovite or biotite) also has basal cleavage; this is why mica can be peeled into thin sheets. Prismatic cleavage occurs when there are two cleavage planes in a crystal that intersect at 90 degrees. Spodumene exhibits ...
Pores and crystallites tend to have straight grain boundaries following dense planes; cleavage; dislocations (plastic deformation) the dislocation core tends to spread on dense planes (the elastic perturbation is "diluted"); this reduces the friction (Peierls–Nabarro force), the sliding occurs more frequently on dense planes;
Since the nature of cleavage is dependent on scale, slaty cleavage is defined as having 0.01 mm or less of space occurring between layers. [1] Slaty cleavage often occurs after diagenesis and is the first cleavage feature to form after deformation begins. The tectonic strain must be enough to allow a new strong foliation to form, i.e. slaty ...
Orthoclase, or orthoclase feldspar (endmember formula K Al Si 3 O 8), is an important tectosilicate mineral which forms igneous rock.The name is from the Ancient Greek for "straight fracture", because its two cleavage planes are at right angles to each other.
Perfect basal cleavage as seen in biotite (black), and good cleavage seen in the matrix (pink orthoclase). By definition, minerals have a characteristic atomic arrangement. Weakness in this crystalline structure causes planes of weakness, and the breakage of a mineral along such planes is termed cleavage.
Most common are scalenohedra, with faces in the hexagonal {2 1 1} directions (morphological unit cell) or {2 1 4} directions (structural unit cell); and rhombohedral, with faces in the {1 0 1} or {1 0 4} directions (the most common cleavage plane). [10] Habits include acute to obtuse rhombohedra, tabular habits, prisms, or various scalenohedra.
Twenty-two percent voted for the second, and 11 percent said cleavage is passé. Only cleavage isn't really a fashion trend; it's a natural part of the human body. Internet users were quick to ...
The following cleavage planes are centered on this axis and result in the two halves being mirror images of one another. In bilateral holoblastic cleavage, the divisions of the blastomeres are complete and separate; compared with bilateral meroblastic cleavage, in which the blastomeres stay partially connected.