crossed Nicols

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• crossed nicols — noun plural Usage: often capitalized N : two nicol prisms placed one in front of the other and so oriented that their transmission planes for plane polarized light are at right angles with the result that light transmitted by one is stopped by… …   Useful english dictionary

• Optical mineralogy — A petrographic microscope, which is an optical microscope fitted with cross polarizing lenses, a conoscopic lens, and compensators (plates of anisotropic materials; gypsum plates and quartz wedges are common), for crystallographic analysis.… …   Wikipedia

• Spherulite — Spherulites, in petrology, are small, rounded bodies that commonly occur in vitreous igneous rocks. They are often visible in specimens of obsidian, pitchstone and rhyolite as globules about the size of millet seed or rice grain, with a duller… …   Wikipedia

• Natrolite — General Category Tectosilicate Chemical formula Na2Al …   Wikipedia

• Nicol prism — A Nicol prism A Nicol prism is a type of polarizer, an optical device used to produce a polarized beam of light from an unpolarized beam. See polarized light. It was the first type of polarizing prism to be invented, in 1828 by William Nicol… …   Wikipedia

• Quartz-porphyry — Quartz porphyry, in petrology, is the name given to a group of hemi crystalline acid rocks containing porphyritic crystals of quartz in a fine grained matrix, usually of micro crystalline or felsitic structure. In specimens, the quartz appears as …   Wikipedia

• XN — may refer to* crossed Nicols, see Nicol prism * the two letter code of the Nordic Patent Institute World Intellectual Property Organization, [http://www.wipo.int/edocs/pctndocs/en/2007/pct news 2007 12.pdf Nordic Patent Institute to Start… …   Wikipedia

• anisotropic — adj as used in Test Method D5061, exhibiting optical properties of different values when viewed with an optical microscope having mutually exclusive polarized light, for example, crossed nicols. D5061 …   Coke&Coal Terminology

• isotropic phase — n as used in Test Method D5061, a binderphase carbon texture that exhibits optical properties that are the same in all directions when viewed with an optical microscope having mutually exclusive polarized light, for example, crossed nicols. D5061 …   Coke&Coal Terminology

• interference figure — noun : a figure observed with a conoscope when a section of a doubly refracting crystal is in the path traversed by convergent plane polarized light (as when a centered black cross is superimposed over a black spot at the center of a series of… …   Useful english dictionary

• Pompey — For other uses, see Pompey (disambiguation). Gnaeus Pompeius Magnus Roman statue of Pompey, at the Villa Arconati a Castellazzo di Bollate (Milan, Italy). It was brought there from Rome in 1627 by Galeazzo Arconati. Born September 29, 106 BC …   Wikipedia