- a transparent variety of calcite that is double-refracting and is used as a polarizer.
Origin of Iceland spar
First recorded in 1820–30
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- a pure transparent variety of calcite with double-refracting crystals used in making polarizing microscopes
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
- 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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