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

In 1808 Malus, looking through Iceland spar at the sun, reflected from the window of the Luxembourg Palace in Paris, discovered the polarization of light by reflection.

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

Spar, sp�r, n. a term applied by miners to any bright crystalline mineral, and adopted by mineralogists in the names of a number of minerals—calcareous spar, fluor spar, Iceland spar, &c.—adj.

From Chambers's Twentieth Century Dictionary (part 4 of 4: S-Z and supplements) by Various

Schists and different productions of limestone were found in abundance, as was also a sort of strange, transparent, colorless crystal, which has a refraction peculiar to Iceland spar.

From The Voyages and Adventures of Captain Hatteras by Riou, Edouard

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