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

In Iceland spar there is one direction round which the crystalline molecules are symmetrically built.

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

The double refraction of Iceland spar was first treated in a work published by Erasmus Bartholinus, in 1669.

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