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Phosphorus is a chemical element with the symbol P and the atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Earth. It has an occurrence in the Earth's crust of about 0.1%, generally occurring as phosphate in ...
White phosphorus is also the most common, industrially important, and easily reproducible allotrope, and for these reasons is regarded as the standard state of phosphorus. The most stable form is the black allotrope , which is a metallic looking, brittle and relatively non-reactive semiconductor (unlike the white allotrope, which has a white or ...
Phosphorus, as black phosphorus. Phosphorus in its most thermodynamically stable black form, is a lustrous and comparatively unreactive solid with a density of 2.69 g/cm 3, and is soft (MH 2.0) and has a flaky comportment. It sublimes at 620 °C. Black phosphorus has an orthorhombic crystalline structure (CN 3).
If crystals of rutile have grown in the crystal of apatite, in the right light the cut stone displays a cat's-eye effect. Major sources for gem apatite are [ 3 ] Brazil, Myanmar, and Mexico. Other sources include [ 3 ] Canada, Czech Republic, Germany, India, Madagascar, Mozambique, Norway, South Africa, Spain, Sri Lanka, and the United States.
A generalization is that minerals with metallic or adamantine lustre tend to have higher specific gravities than those having a non-metallic to dull lustre. For example, hematite , Fe 2 O 3 , has a specific gravity of 5.26 [ 89 ] while galena , PbS, has a specific gravity of 7.2–7.6, [ 90 ] which is a result of their high iron and lead ...
Physically, they are shiny, brittle solids with intermediate to relatively good electrical conductivity and the electronic band structure of a semimetal or semiconductor. Chemically, they mostly behave as (weak) nonmetals, have intermediate ionization energies and electronegativity values, and amphoteric or weakly acidic oxides .
Dull (or earthy) minerals exhibit little to no lustre, due to coarse granulations which scatter light in all directions, approximating a Lambertian reflector. An example is kaolinite . [ 3 ] A distinction is sometimes drawn between dull minerals and earthy minerals, [ 4 ] with the latter being coarser, and having even less lustre.
This type of environment is the main reason why phosphorites are commonly associated with silica and chert. Estuaries are also known as a phosphorus “trap”. This is because coastal estuaries contain a high productivity of phosphorus from marsh grass and benthic algae which allow an equilibrium exchange between living and dead organisms. [11]