Search results
Results From The WOW.Com Content Network
Roundness is an important indicator of the genetic affiliation of a clastic rock. The degree of roundness points to the range and mode of transport of clastic material, and can also serve as a search criterion in mineral exploration, especially for placer deposits. Alluvial debris in major rivers tend to exhibit a high degree of roundness ...
Schematic representation of difference in grain shape. Two parameters are shown: sphericity (vertical) and rounding (horizontal).. Sphericity is a measure of how closely the shape of an object resembles that of a perfect sphere.
Roundness is the measure of how closely the shape of an object approaches that of a mathematically perfect circle. Roundness applies in two dimensions , such as the cross sectional circles along a cylindrical object such as a shaft or a cylindrical roller for a bearing .
The more rounded the grain is, the lower the angle of repose. A decrease in roundness, or an increase in angularity, results in interlocking via particle contact. This linear relationship between the angle of repose and the roundness of grain can also be used as a predictor of the angle of repose if the roundness of the grain is measured. [5]
In sedimentary geology, maturity describes the composition and texture of grains in clastic rocks, most typically sandstones, resulting from different amounts of sediment transportation. A sediment is mature when the grains in a sediment become well-sorted and well-rounded due to weathering or abrasion of the grains during transport.
This approach is used widely in mineralogy, ore geology and general geological mapping. [2] The following tests are some examples of those that are used on hand specimens, or on field samples, or on thin sections with the aid of a polarizing microscope. Color; Color of the mineral. Color alone is not diagnostic.
Sedimentary textures include the degree of sorting, grading, shape and roundness of the clasts. [22] Metamorphic textures include those referring to the timing of growth of large metamorphic minerals relative to a phase of deformation—before deformation porphyroclast —after deformation porphyroblast . [ 23 ]
The degree of sorting is determined by the range of grain sizes in a sediment deposit and is the result of various transport processes (rivers, debris flow, wind, glaciers, etc.). This should not be confused with crystallite size, which refers to the individual size of a crystal in a solid. Crystallite is the building block of a grain.