Iceland spar from Helgustadir: geology, mineralogy and the influence to science development

Research Collaboratores:
Dipl. Geol. Simon Spürgin, Hauri, Mineralstoffwerk, Bötzingen, Germany,
Dr. Runes S. Selbekk, Natural Museum Oslo, Norway

The rock formations exposed in Iceland consists mostly of basalt lava sequences erupted from fissures or within central-volcanoes. Low-temperatures alteration minerals like zeolites and calcite are abundant in the tertiary basalts, especially in zones of alteration associated with central volcanoes. A site at Helgustadir (65°0´, 14°01´), Reydarfjördur  supplied large quantities of transparent cleavage rhombs of calcite (commonly called Iceland spar). These crystals played a significant role in the early development of several fields in the physical sciences. Reference: Weisenberger T., Spürgin S. & Selbekk R.S. (2008) Die Fundstelle Helgustadir (Island): Geologie, Mineralogie und die bedeutende Geschichte des Isländischen Doppelspats für die Wissenschaft. Aufschluss 1, 53-63

Fig. 1: Helgustadir road sign

Fig. 2: Map of low temeprature alteration in East Iceland

Fig. 3: Iceland spar