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

Dove's Iceland spar prism is also useful, when two pigments have to be worked on to paper, so as to be complementary.

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

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

After three days he worked with common electricity, trying glass, heavy optical glass, quartz, Iceland spar, all without effect, as on former trials.

From Encyclopaedia Britannica, 11th Edition, Volume 10, Slice 2 "Fairbanks, Erastus" to "Fens" by Various

Malus made this discovery in 1808, while looking through Iceland spar at the light of the sun reflected from the windows of the Luxembourg palace in Paris.

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