page_title: Sunstone (medieval)
hierarchical_section_title: Sunstone (medieval)
caption_attribution_description: Iceland spar, perhaps the medieval sunstone.
context_page_description: The sunstone is a type of mineral attested in several 13th–14th century written sources in Iceland, one of which describes its use to locate the sun in a completely overcast sky. Sunstones are also mentioned in the inventories of several churches and one monastery in 14th–15th century Iceland and Germany.
  A theory exists that the sunstone had polarizing attributes and was used as a navigation instrument by seafarers in the Viking Age. A stone found in 2013 off Alderney, in the wreck of a 16th-century warship, may lend evidence of the existence of sunstones as navigational devices.
context_section_description: The sunstone (Icelandic: sólarsteinn) is a type of mineral attested in several 13th–14th century written sources in Iceland, one of which describes its use to locate the sun in a completely overcast sky. Sunstones are also mentioned in the inventories of several churches and one monastery in 14th–15th century Iceland and  Germany.
  A theory exists that the sunstone had polarizing attributes and was used as a navigation instrument by seafarers in the Viking Age. A stone found in 2013 off Alderney, in the wreck of a 16th-century warship, may lend evidence of the existence of sunstones as navigational devices.
caption: Iceland spar, possibly the Icelandic medieval sunstone used to locate the sun in the sky when obstructed from view.
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