Iceland spar

American  

noun

1. a transparent variety of calcite that is double-refracting and is used as a polarizer.

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Iceland spar British  

noun

1. a pure transparent variety of calcite with double-refracting crystals used in making polarizing microscopes

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Iceland spar Scientific  

/ īs′lənd /

1. A form of calcite that is transparent and causes light passing through it to refract in two directions (forming a double image of an object seen through it). Iceland spar occurs in perfect rhombohedrons and is used in optical instruments.

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Etymology

Origin of Iceland spar

First recorded in 1820–30

Example Sentences

See Examples For:

Iceland spar

Discovered in the 17th Century, polarization has become an elaborate science using small, costly, natural crystals like Iceland spar.

From Time Magazine Archive

Here we are helped by the property of Iceland spar, which is able to split up a ray into two divergent rays.

From Colour Measurement and Mixture by Abney, W. de W.

Place a piece of Iceland spar over a dot of ink; two dots are seen, the one appearing nearer than the other to the eye.

From Six Lectures on Light Delivered In The United States In 1872-1873 by Tyndall, John

By means of Iceland spar cut in the proper direction, double refraction is capable of easy illustration.

From Six Lectures on Light Delivered In The United States In 1872-1873 by Tyndall, John

Hence, if a plate be cut from a crystal of Iceland spar perpendicular to the axis, all rays sent across this plate in the direction of the axis will produce but one image.

From Six Lectures on Light Delivered In The United States In 1872-1873 by Tyndall, John