Sunstone (medieval)
Encyclopedia
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. A theory exists that the sunstone had polarizing
attributes and was used as a navigation
instrument by seafarers in the Viking Age
.
source in Iceland, "Rauðúlfs þáttr
", mentions the sunstone as a mineral by means of which the sun could be located in an overcast and snowy sky by holding it up and noting where it emitted, reflected or transmitted light (hvar geislaði úr honum). Sunstones are also mentioned in Hrafns saga Sveinbjarnarsonar (13th century) and in church and monastic inventories (14th–15th century) without discussing their attributes. The sunstone texts of Hrafns saga Sveinbjarnarsonar were copied to all four versions of the medieval hagiography
Guðmundar saga góða
.
The description in "Rauðúlfs þáttr" of the use of the sunstone is as follows:
s, recalling the horsemen of the Apocalypse
. It has been suggested that the horsemen of Hrafns saga contain allegorical allusions to the winter solstice
and the four elements
as an omen of Hrafn’s death, where the sunstone also appears.
"Rauðúlfs þáttr", a tale of Saint Olav, and the only medieval source mentioning how the sunstone was used, is a thoroughly allegorical work. A round and rotating house visited by Olav has been interpreted as a model of the cosmos
and the human soul
, as well as a prefiguration of the Church. The intention of the author was to achieve an apotheosis
of St. Olav, through placing him in the symbolic seat of Christ
. The house belongs to the genre
of "abodes of the sun," which seemed widespread in medieval literature. St. Olav used the sunstone to confirm the time reckoning skill of his host right after leaving this allegorical house. He held the sunstone up against the snowy and completely overcast sky and noted where light was emitted from it (the Icelandic words used do not make it clear whether the light was reflected by the stone, emitted by it or transmitted through it). It has been suggested that in Rauðúlfs þáttr the sunstone was used as a symbol of the Virgin
, following a widespread tradition in which the virgin birth of Christ is compared with glass letting a ray of the sun through.
The allegories of the above mentioned texts exploit the symbolic value of the sunstone, but the church and monastic inventories, however, show that something called sunstones did exist as physical objects in Iceland. The presence of the sunstone in "Rauðúlfs þáttr" may be entirely symbolic but its use is described in sufficient detail to show that the idea of using a stone to find the sun's position in overcast conditions was commonplace.
or Iceland spar
) that polarize
light and by which the azimuth of the sun can be determined amid a partly overcast sky or when the sun is just below the horizon. The principle is used by many animals and was applied during polar flights
before more advanced techniques became available. Ramskou further conjectured that the sunstone could have aided navigation in the open sea in the Viking period. This idea has become very popular, but no extant records of the use of a sunstone for navigation exist in the medieval literature, and used alone, a polarizing mineral only gives the horizontal angle of the sun (azimuth), which is only of marginal value when navigating the open sea. A polarizing crystal
would have been useful as a sundial
, especially at high latitude
s with extended hours of twilight, in mountainous areas or in partly overcast conditions, although only in conjunction with known landmarks; churches and monasteries would have valued such an object as an aid to keep track of the canonical hours
.
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
attested in several 13th–14th century written sources in Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...
, 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
Monastery
Monastery denotes the building, or complex of buildings, that houses a room reserved for prayer as well as the domestic quarters and workplace of monastics, whether monks or nuns, and whether living in community or alone .Monasteries may vary greatly in size – a small dwelling accommodating only...
in 14th–15th century Iceland. A theory exists that the sunstone had polarizing
Polarizer
A polarizer is an optical filter that passes light of a specific polarization and blocks waves of other polarizations. It can convert a beam of light of undefined or mixed polarization into a beam with well-defined polarization. The common types of polarizers are linear polarizers and circular...
attributes and was used as a navigation
History of navigation
In the pre-modern history of human migration and discovery of new lands by navigating the oceans, a few peoples have excelled as sea-faring explorers...
instrument by seafarers in the Viking Age
Viking Age
Viking Age is the term for the period in European history, especially Northern European and Scandinavian history, spanning the late 8th to 11th centuries. Scandinavian Vikings explored Europe by its oceans and rivers through trade and warfare. The Vikings also reached Iceland, Greenland,...
.
Sources
One medievalHigh Middle Ages
The High Middle Ages was the period of European history around the 11th, 12th, and 13th centuries . The High Middle Ages were preceded by the Early Middle Ages and followed by the Late Middle Ages, which by convention end around 1500....
source in Iceland, "Rauðúlfs þáttr
Rauðúlfs þáttr
Rauðúlfs þáttr is a short allegorical story preserved in Iceland in a number of medieval manuscripts. The author is unknown but was apparently a 12th–13th century ecclesiastical person...
", mentions the sunstone as a mineral by means of which the sun could be located in an overcast and snowy sky by holding it up and noting where it emitted, reflected or transmitted light (hvar geislaði úr honum). Sunstones are also mentioned in Hrafns saga Sveinbjarnarsonar (13th century) and in church and monastic inventories (14th–15th century) without discussing their attributes. The sunstone texts of Hrafns saga Sveinbjarnarsonar were copied to all four versions of the medieval hagiography
Hagiography
Hagiography is the study of saints.From the Greek and , it refers literally to writings on the subject of such holy people, and specifically to the biographies of saints and ecclesiastical leaders. The term hagiology, the study of hagiography, is also current in English, though less common...
Guðmundar saga góða
Guðmundur Arason
Guðmundur Arason was an influential 12th and 13th century Icelandic saintly bishop who took part in increasing the powers of the Catholic Church in medieval Iceland. His story is recorded in several manuscripts, most notably Prestssaga Guðmundar góða...
.
The description in "Rauðúlfs þáttr" of the use of the sunstone is as follows:
- Thorsteinn Vilhjalmsson translation:
- The weather was thick and snowy as Sigurður had predicted. Then the king summoned Sigurður and Dagur (Rauðúlfur's sons) to him. The king made people look out and they could nowhere see a clear sky. Then he asked Sigurður to tell where the sun was at that time. He gave a clear assertion. Then the king made them fetch the solar stone and held it up and saw where light radiated from the stone and thus directly verified Sigurður’ s prediction.
In Icelandic: "Veður var þykkt og drífanda sem Sigurður hafði sagt. Þá lét konungur kalla til sín Sigurð og Dag. Síðan lét konungur sjá út og sá hvergi himin skýlausan. Þá bað hann Sigurð segja hvar sól mundi þá komin. Hann kvað glöggt á. Þá lét konungur taka sólarstein og hélt upp og sá hann hvar geislaði úr steininum og markaði svo beint til sem Sigurður hafði sagt".
Allegorical nature of the medieval texts
Two of the original medieval texts on the sunstone are allegorical. Hrafns saga Sveinbjarnarsonar contains a burst of purely allegorical material associated with Hrafn’s slaying. This involves a celestial vision with three highly cosmological knightKnight
A knight was a member of a class of lower nobility in the High Middle Ages.By the Late Middle Ages, the rank had become associated with the ideals of chivalry, a code of conduct for the perfect courtly Christian warrior....
s, recalling the horsemen of the Apocalypse
Apocalypse
An Apocalypse is a disclosure of something hidden from the majority of mankind in an era dominated by falsehood and misconception, i.e. the veil to be lifted. The Apocalypse of John is the Book of Revelation, the last book of the New Testament...
. It has been suggested that the horsemen of Hrafns saga contain allegorical allusions to the winter solstice
Winter solstice
Winter solstice may refer to:* Winter solstice, astronomical event* Winter Solstice , former band* Winter Solstice: North , seasonal songs* Winter Solstice , 2005 American film...
and the four elements
Classical element
Many philosophies and worldviews have a set of classical elements believed to reflect the simplest essential parts and principles of which anything consists or upon which the constitution and fundamental powers of anything are based. Most frequently, classical elements refer to ancient beliefs...
as an omen of Hrafn’s death, where the sunstone also appears.
"Rauðúlfs þáttr", a tale of Saint Olav, and the only medieval source mentioning how the sunstone was used, is a thoroughly allegorical work. A round and rotating house visited by Olav has been interpreted as a model of the cosmos
Cosmos
In the general sense, a cosmos is an orderly or harmonious system. It originates from the Greek term κόσμος , meaning "order" or "ornament" and is antithetical to the concept of chaos. Today, the word is generally used as a synonym of the word Universe . The word cosmos originates from the same root...
and the human soul
Soul
A soul in certain spiritual, philosophical, and psychological traditions is the incorporeal essence of a person or living thing or object. Many philosophical and spiritual systems teach that humans have souls, and others teach that all living things and even inanimate objects have souls. The...
, as well as a prefiguration of the Church. The intention of the author was to achieve an apotheosis
Apotheosis
Apotheosis is the glorification of a subject to divine level. The term has meanings in theology, where it refers to a belief, and in art, where it refers to a genre.In theology, the term apotheosis refers to the idea that an individual has been raised to godlike stature...
of St. Olav, through placing him in the symbolic seat of Christ
Christ
Christ is the English term for the Greek meaning "the anointed one". It is a translation of the Hebrew , usually transliterated into English as Messiah or Mashiach...
. The house belongs to the genre
Genre
Genre , Greek: genos, γένος) is the term for any category of literature or other forms of art or culture, e.g. music, and in general, any type of discourse, whether written or spoken, audial or visual, based on some set of stylistic criteria. Genres are formed by conventions that change over time...
of "abodes of the sun," which seemed widespread in medieval literature. St. Olav used the sunstone to confirm the time reckoning skill of his host right after leaving this allegorical house. He held the sunstone up against the snowy and completely overcast sky and noted where light was emitted from it (the Icelandic words used do not make it clear whether the light was reflected by the stone, emitted by it or transmitted through it). It has been suggested that in Rauðúlfs þáttr the sunstone was used as a symbol of the Virgin
Mary (mother of Jesus)
Mary , commonly referred to as "Saint Mary", "Mother Mary", the "Virgin Mary", the "Blessed Virgin Mary", or "Mary, Mother of God", was a Jewish woman of Nazareth in Galilee...
, following a widespread tradition in which the virgin birth of Christ is compared with glass letting a ray of the sun through.
The allegories of the above mentioned texts exploit the symbolic value of the sunstone, but the church and monastic inventories, however, show that something called sunstones did exist as physical objects in Iceland. The presence of the sunstone in "Rauðúlfs þáttr" may be entirely symbolic but its use is described in sufficient detail to show that the idea of using a stone to find the sun's position in overcast conditions was commonplace.
Sunstones for orientation and navigation?
Danish archaeologist Thorkild Ramskou posited that the sunstone could have been one of the minerals (cordieriteCordierite
Cordierite or iolite is a magnesium iron aluminium cyclosilicate. Iron is almost always present and a solid solution exists between Mg-rich cordierite and Fe-rich sekaninaite with a series formula: 2 to 2...
or Iceland spar
Iceland spar
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...
) that polarize
Polarizer
A polarizer is an optical filter that passes light of a specific polarization and blocks waves of other polarizations. It can convert a beam of light of undefined or mixed polarization into a beam with well-defined polarization. The common types of polarizers are linear polarizers and circular...
light and by which the azimuth of the sun can be determined amid a partly overcast sky or when the sun is just below the horizon. The principle is used by many animals and was applied during polar flights
Polar route
A polar route refers to an aircraft route across the uninhabited polar ice cap region. The American Federal Aviation Administration defines the North Polar area of operations as the area lying north of 78 deg north latitude , which is entirely north of Alaska and most of Siberia...
before more advanced techniques became available. Ramskou further conjectured that the sunstone could have aided navigation in the open sea in the Viking period. This idea has become very popular, but no extant records of the use of a sunstone for navigation exist in the medieval literature, and used alone, a polarizing mineral only gives the horizontal angle of the sun (azimuth), which is only of marginal value when navigating the open sea. A polarizing crystal
Pleochroism
Pleochroism is an optical phenomenon in which a substance appears to be different colors when observed at different angles with polarized light.- Background :Anisotropic crystals will have optical properties that vary with the direction of light...
would have been useful as a sundial
Sundial
A sundial is a device that measures time by the position of the Sun. In common designs such as the horizontal sundial, the sun casts a shadow from its style onto a surface marked with lines indicating the hours of the day. The style is the time-telling edge of the gnomon, often a thin rod or a...
, especially at high latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
s with extended hours of twilight, in mountainous areas or in partly overcast conditions, although only in conjunction with known landmarks; churches and monasteries would have valued such an object as an aid to keep track of the canonical hours
Canonical hours
Canonical hours are divisions of time which serve as increments between the prescribed prayers of the daily round. A Book of Hours contains such a set of prayers....
.