Helgustadir mine

Helgustadir mine (Icelandic: Helgustaðanáma [ˈhɛlkʏˌstaːðaˌnauːma]) is a mine in the east of Iceland where Iceland spar (a form of transparent calcite) was mined from the mid-17th century to the 20th century. It is the source of the largest and clearest known Iceland spar specimen and the source of most museum specimens of Iceland spar.

It was declared a nature reserve in 1975.