An occurence of optical-grade calcite known since 1669. "Iceland spar" was mined in a organized way from 1855. Regular mining endend in 1925. In 1975 the location received the status of a "natural monument".
Located near Helgustađir farm, 7 km E of Eskijördur (Eskifjord) town (note, however, that Eskijördur is also the northern branch of Reydarfjordur and the name of a farm), in Reydarfjord.
The locality is also famous for zeolites, especially stilbite.
Refs.:
- Kristjansson, Leo (2002) Iceland spar: The Helgustadir Calcite Locality and its Influence on the Development of Science - Journal of Geoscience Education, Vol. 50 No. 4, 419-426
- http://serc.carleton.edu/files/nagt/jge/abstracts/Kristjansson_v50n4p419.pdf
- http://giantcrystals.strahlen.org/europe/helgustadir.htm
Helgustadir Iceland Spar Mine - by Daniel Russell