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Specimen: Iceland Spar Calcite Double Refraction

Type: Mineral/Crystal

Location: China

Scale cube=1cm: Full sizing please see photo

Iceland spar, formerly known as Iceland crystal, is a transparent variety of calcite, or crystallized calcium carbonate, originally brought from Iceland and used in demonstrating the polarization of light. It occurs in large readily cleavable crystals, easily divisible into rhombs, and is remarkable for its birefringence. This means that the index of refraction of the crystal is different for light of different polarization. A ray of unpolarized light passing through the crystal divides into two rays of perpendicular polarization directed at different angles, called double refraction. So objects seen through the crystal appear doubled. Famously discovered in Iceland, hence its name, Iceland Spar can also be found in USA, Mexico and China.

Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate). Calcite is a common constituent of sedimentary rocks, limestone in particular, much of which is formed from the shells of dead marine organisms. Approximately 10% of sedimentary rock is limestone.

ACTUAL AS SEEN: The image shows the EXACT specimen you will receive. The specimen has been carefully hand selected and photographed. Measurements are as accurate as possible, though be aware measuring precise dimensions can be difficult from irregular shaped items. Whilst we portray colours as close to life-like as we can, colours will vary if taken in sunlight, indoors, from monitor to monitor and device to device. Once this specimen is sold, we will update this listing with new similar selected item, with a new photo and dimensions.