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Classic doublespar crystals from Helgustadir on a recent stamp

Photo Source : Icelandic Post

Icelandic Spar (Calcite) up to 7 meter from Helgustadir, Iceland

Coordinates : 65°02'N , 13°50'W : Helgustadir, Outer Reydarfjördur, Central Eastern Iceland

To see the Helgustadir on Google Earth, please click here.

 

- Giant Iceland Spar / Calcite from Helgustadir, Iceland -

 

Helgustadir is the name of a farmsite on the Northern shore of the Reydarfjordur in the extreme East of Iceland. This deposit of outstanding transparent calcite was discovered in the 17th century and was intermittently mined for many decades until 1924. The transparency of the crystals were ideally suited for the optical industry and therefore the calcite quickly became famous as "Iceland spar" and its marvelous crystals were rapidly distributed among the leading European scientists of that time. The initial concepts of double refraction and crystal cleavage planes were first discovered on calcite crystals from this site and led to a far better understanding of crystal physics. Hence Helgustadir is one of those classic sites, which started mineralogy as a serious science.

The calcite crystals, which are accompanied by small tufts of stilbite crystals reach a size of several meters. RÖSLER (1981 : Lehrbuch der Mineralogie) quotes a maximum size of 6 x 2 m , but dont give any more details. Other authors describe 7 x 7 x 2 m large crystals. A crystal of 230 kg is said to be on display in the exhibition of the Museum of Natural History in London.

Today there remain large dumps of the former mining activity, whereas the mine as such is most of the year filled with snow and more or less inacessible. It is still possible to find small scattered cleavage pieces of double spar calcite on the dumps, especially after periods of heavy rain, which is not a rarity in Iceland. However collecting in this mine is forbidden by law, as Helgustadir was declared a national heritage site in 1975.

Courtesy of L. Kristjansson a detailed publication about the Helgustadir Iceland Spar locality and its scientitic history is available here.

Iceland Spar in a Nutshell :


Mineralogy :

Calcite with minor zeolites

Crystal Size :

7 x 7 x 2 meter confirmed


Geology & Origin :

Hydrothermal crevice fillings in basaltic rock of tertiary age,possibly partly pneumatolytic


Current status :

Open air, the mine pit is often inaccessible due to snow conditions. Dumps of former mining activity.


Remarks :

A famous place of eminent importance to the history of natural sciences

 

 

Resources and Relevant Weblinks :

For more information on the mineral calcite please look at www.mindat.org, Webmineral and the german Mineralienatlas.

Strange enough, scientific interest in the Helgustadir site ceased almost completely in the 20th century. The most modern literature survey about the Helgustadir site and its influence on the scientific community was recently compiled by Dr. Leo Kristjansson who works at the Geophysics Department of Iceland university. It can be found here.

Please have also a look at his website, where you can find his extensive literature survey about Helgustadir and other research projects.

 

 

 

Snow filled Helgustadir mine site in April

Photo : Mr. L. Kristjansson

 

Inside the old quarry on a rainy day.
Note the white remains of the calcite vein

Photo : Mr. L. Kristjansson

 

Slightly weathered calcite crystals from the Helgustadir mine

Photo : Flaviano, on www.flickr.com

 

 

 

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