To: Graewoulf
Iceland spar is a clear, crystalized form of calcite. It is best know for its property of double refraction.
6 posted on
11/01/2011 10:11:36 PM PDT by
ApplegateRanch
("Public service" does NOT mean servicing the people, like a bull among heifers.)
To: ApplegateRanch
I did research on this topic and it's quite interesting that the Vikings could navigate even on cloudy days with no sun to guide them, with the aid of a sunstone.
7 posted on
11/01/2011 10:30:19 PM PDT by
Ciexyz
To: ApplegateRanch
Thanks! Another great, and useful compound filled to the brim with CO2! (CaO+CO2).
9 posted on
11/02/2011 6:06:38 AM PDT by
Graewoulf
( obama"care" violates the 1890 Sherman Anti-Trust Law, AND is illegal by the U.S. Constitution.)
To: ApplegateRanch; decimon
The term "sunstone" is a bit confusing to those like me who work with minerals. It generally refers to a type of gem-quality labradorite or andesine feldspar found in Oregon, India and Tanzania mainly. Optical calcite is very different stuff. In the referenced article the name refers to any mineral used by the Vikings to locate the sun for navigation purposes.
It's long been believed that the mineral iolite (cordierite) was used for Viking navigation. A friend who comes from strong Nordic roots and is an accomplished gemologist/mineralogist put together this nice explanation on her website: Viking Sunstone
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