Iceland spar
[13] Iceland spar can produce vivid colours when viewed under polarized light due to its birefringent nature.
[15][16] Additionally, Iceland spar is optically active, meaning it can rotate the plane of polarization of light passing through it, a property resulting from its asymmetrical atomic arrangement.
[19] The study of double refraction in Iceland spar played a role in developing the wave theory of light.
Scientists such as Christiaan Huygens,[20] Isaac Newton, and Sir George Stokes studied this phenomenon and contributed to the understanding of light as a wave.
[24] The understanding of double refraction in Iceland spar also led to the development of polarized light microscopy, which is used in various scientific fields to study the properties of materials.
[32] Field mapping of surface geology and mineralogy also plays a role in identifying potential mineralization zones.
[35] Once extracted, the calcite is processed to remove impurities, prepared for various applications, including optical instruments and jewelry, and used as a source of calcium carbonate in industries like construction and agriculture.
[41] The high noise levels generated by mining activities can cause hearing loss over time if proper protective measures are not in place.
[41] The demanding nature of mining work, along with long hours and isolation, can contribute to mental health issues such as stress, anxiety, and depression.
[41] Regularly monitoring air quality, noise levels, and other potential hazards is essential to ensure a safe working environment.
[44][45] While uncommon, Iceland spar has historically been used in navigation as a polarizing filter to determine the sun's direction on overcast days.
[43][47] The polarization of sunlight in the Arctic can be detected,[46] and the direction of the sun identified to within a few degrees in both cloudy and twilight conditions using the sunstone and the naked eye.
[48] The process involves moving the stone across the visual field to reveal a yellow entoptic pattern on the fovea of the eye, probably Haidinger's brush.
The recovery of an Iceland spar sunstone from a ship of the Elizabethan era that sank in 1592 off Alderney suggests that this navigational technology may have persisted after the invention of the magnetic compass.
[52] Iceland spar is also used in optical instruments for geological and biological microscopy as its birefringence helps to reveal material structure.
[59] Due to their scientific and historical significance, conservation efforts related to Iceland spar primarily focus on preserving specimens and mining sites.
