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

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

From Time Magazine Archive

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

We have seen and examined the two beams emergent from Iceland spar, and have proved them to be polarized.

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

It was shown by Brewster that certain natural specimens of Iceland spar are traversed by thin twin strata.

From Scientific American Supplement, No. 711, August 17, 1889 by Various

An able optician, named Nicol, cut a crystal of Iceland spar in two halves in a certain direction.

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