Posted on 03/08/2013 11:05:59 AM PST by Red Badger
A rough, whitish block recovered from an Elizabethan shipwreck may be a sunstone, the fabled crystal believed by some to have helped Vikings and other medieval seafarers navigate the high seas, researchers say.
In a paper published earlier this week, a Franco-British group argued that the Alderney Crystal—a chunk of Icelandic calcite found amid a 16th century wreck at the bottom of the English Channel—worked as a kind of solar compass, allowing sailors to determine the position of the sun even when it was hidden by heavy cloud, masked by fog, or below the horizon.
That's because of a property known as birefringence, which splits light beams in a way that can reveal the direction of their source with a high degree of accuracy. Vikings may not have grasped the physics behind the phenomenon, but that wouldn't present a problem.
"You don't have to understand how it works," said Albert Le Floch, of the University in Rennes in western France. "Using it is basically easy." Vikings were expert navigators—using the sun, stars, mountains and even migratory whales to help guide them across the sea—but some have wondered at their ability to travel the long stretches of open water between Greenland, Iceland, and Newfoundland in modern-day Canada.
Le Floch is one of several who've suggested that calcite crystals were used as navigational aids for long summer days in which the sun might be hidden behind the clouds. He said the use of such crystals may have persisted into the 16th century, by which time magnetic compasses were widely used but often malfunctioned. Le Floch noted that one Icelandic legend—the Saga of St. Olaf—appears to refer to such a crystal when it says that Olaf used a "sunstone" to verify the position of the sun on a snowy day. But that's it. Few other medieval references to sunstones have been found, and no such crystals have ever been recovered from Viking tombs or ships. Until the Alderney Crystal was recovered in 2002, there had been little if any hard evidence to back the theory.
Many specialists are still skeptical. Donna Heddle, the director of the Center for Nordic Studies at Scotland's University of the Highlands and Islands, described the solar compass hypothesis as speculative. "There's no solid evidence that that device was used by Norse navigators," she said Friday. "There's never been one found in a Viking boat. One cannot help but feel that if there were such things they would be found in graves." She acknowledged that the crystal came from Iceland and was found near a navigation tool, but said it might just as easily have been used as a magnifying device as a solar compass. Le Floch argued that one of the reasons why no stones have been found before is that calcite degrades quickly—it's vulnerable to acid, sea salts, and to heat.
The Alderney Crystal was originally transparent, but the sea water had turned it a milky white. Le Floch's paper—written with Guy Ropars, Jacques Lucas, and a group of Britons from the Alderney Maritime Trust—appeared Wednesday in the Proceedings of the Royal Society A.
Read more at: http://phys.org/news/2013-03-fabled-sunstone.html#jCp
This photo taken in Alderney, one of the Channel Islands, dated June 2012 and released on Friday March 8, 2013 by scientist Guy Ropars shows the Alderney Crystal, a piece of calcite. Researchers say the rough, whitish crystal recovered from the wreckage of 16th century English warship may be a sunstone, a special kind of mineral believed by some to have helped medieval seafarers navigate the high seas. (AP Photo/Guy Ropars)
GGG Ping!...........
Release the Kraken!!!
A natural beam splitter?
“Le Floch noted that one Icelandic legend—the Saga of St. Olaf—appears to refer to such a crystal when it says that Olaf used a “sunstone” to verify the position of the sun on a snowy day.”
I hope that all this speculation regarding sunstones isnt due to a single reference in some guy’s journal. If thats the case sunstones have about the same credibility as bigfoot. It would also reinforce my suspicion that archaeologists have far too much time on their hands.
Many stone have birefringence but I was taught Iolite (Cordierite) was use as “sunstones” by Vikings. They were used in pairs as crossed polarloid filters to produce a dark field similar to welding goggles becuase of the the gemstone’s extreme pleochroism, not birefringence.
I read a sci-fi story once with a female archaeologist digging up an old Viking boat with it's crew and the men came to life. After a few days of driving the men around and having them stay at her apartment and humorous interactions and experiences, she asked why they weren't more dazzled at the baffling technology that they were seeing for the first time, one of the Vikings simply stated that, "it was no matter, we had magic in our time also".
Came looking for nearly free and limitless energy. This thread is a Total Heinlein Fail....
Can the suns position in the sky not be estimated by the time of day? Therefore an hour glass could track the Sun from daylight to dark? As long as East and West can be defined?
Who pays for archeologists? Why you do. Most of them are supported by taxes in one form or another. The reason they have too much time on their hands is that they don't have to produce a competitive product to get paid. Sunstone BS doesn't have to be marketable to get the originator paid.
Yes. It's sometimes called "Iceland Spar". Tourist traps and novelty shops of the sort that sell or used to sell various mineral samples commonly sell small pieces of it.
It splits refracts vertically and horizontally polarized light differently, producing a split image. A good sample will be quite clear. Centuries of immersion in seawater would not be good for it.
Ahhh ... that's the big problem, isn't it? Defining longitude is not easy. The development of precise, portable chronometers was driven by the need for such devices to determine longitude.
“The reason they have too much time on their hands is that they don’t have to produce a competitive product to get paid.”
That’s not entirely true. They are supported by grants which are competitively awarded against the proposals of others. My problem with archaeologists is that almost all the time the results of their studies are useless. Did a certain dinosaur have feathers, did the vikings use a sunstone? What sort of wood did some extinct indian tribe use to make a spear? Who gives a Cr@p except that it satisfys someones idle curiosity. It has no practical value, and most of the time the conclusions are based on guesswork and speculation.
Canada Ping!
“If we confined ourselves solely to pursuits that had calculable practical value, life would be very unpleasant.”
Agreed. I do lots of things that have no practical value, but I use my own money.
And they have dirty minds, too...
“Brooklyn Attitude” = “Never need fear sunburn on scalp.”
That’s the kind of guy arrows were made for.
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