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Iceland spar
noun
- a transparent variety of calcite that is double-refracting and is used as a polarizer.
Iceland spar
noun
- a pure transparent variety of calcite with double-refracting crystals used in making polarizing microscopes
Iceland spar
/ īs′lənd /
- 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.
Word History and Origins
Origin of Iceland spar1
Example Sentences
Crystals like calcite, also called Iceland spar, can reveal the direction of polarization, a bit like a prism that reveals the rainbow within white light.
Light from the sky is polarised and, as he discovered in 2011, looking through a piece of Iceland spar reveals the direction of polarisation, and thus the direction of the sun, to within 5°.
Dove's Iceland spar prism is also useful, when two pigments have to be worked on to paper, so as to be complementary.
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.
He and his colleagues have been experimenting with a mineral called Iceland spar.
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