Search results
Results From The WOW.Com Content Network
Silica is an important nutrient utilized by plants, trees, and grasses in the terrestrial biosphere. Silicate is transported by rivers and can be deposited in soils in the form of various siliceous polymorphs. Plants can readily uptake silicate in the form of H 4 SiO 4 for the formation of phytoliths.
Right: Annotated diagram of the left image, showing features of a silicified breccia. In the silicification of woods, silica dissolves in hydrothermal fluid and seeps into lignin in cell walls. Precipitation of silica out of the fluids produces silica deposition within the voids, especially in the cell walls.
In mineralogy, silica (silicon dioxide, SiO 2) is usually considered a silicate mineral rather than an oxide mineral. Silica is found in nature as the mineral quartz , and its polymorphs . On Earth, a wide variety of silicate minerals occur in an even wider range of combinations as a result of the processes that have been forming and re-working ...
At very high pressure, such as exists in the majority of the Earth's rock, even SiO 2 adopts the six-coordinated octahedral geometry in the mineral stishovite, a dense polymorph of silica found in the lower mantle of the Earth and also formed by shock during meteorite impacts.
At microscopic scales, precious opal is composed of silica spheres some 150–300 nm (5.9 × 10 −6 –1.18 × 10 −5 in) in diameter in a hexagonal or cubic close-packed lattice. It was shown by J. V. Sanders in the mid-1960s [ 8 ] [ 9 ] that these ordered silica spheres produce the internal colors by causing the interference and diffraction ...
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula SiO 2, commonly found in nature as quartz. [5] [6] In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant families of materials, existing as a compound of several minerals and as a
On million-year time scales, the carbonate-silicate cycle is a key factor in controlling Earth's climate because it regulates carbon dioxide levels and therefore global temperature. [3] The rate of weathering is sensitive to factors that change how much land is exposed. These factors include sea level, topography, lithology, and vegetation ...
Silcrete (siliceous paleosol) in the Waddens Cove Formation (formed during the Pennsylvanian), Sydney Basin, Nova Scotia. Silcrete is an indurated (resists crumbling or powdering) soil duricrust formed when surface soil, sand, and gravel are cemented by dissolved silica.