Helgustadir mine (Шаблон:Lang-isШаблон:IPA-is) 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.Шаблон:Sfn It is the source of the largest and clearest known Iceland spar specimen and the source of most museum specimens of Iceland spar.[1]
The mine is located near Eskifjörður, east of Iceland.[2] Helgustadir mine consists of two mines, known as the upper and lower mine.[2]
Uses
Crystals from this area are known for exceptional clarity,[2] leading to the mineral being named "Iceland spar".[2]
Iceland spar from Helgustadir mine was used in optical devices used in physics, chemistry, and geology,[2] most importantly Nicol prisms.
Nature reserve
The nature reserve is 0.9 hectares.[2] Since 2010, it has been on the Environment Agency of Iceland's red list of areas that are likely to lose their protection status.[2]
Theft of crystals
Being a nature reserve, tampering with the rock formations and removing crystals is forbidden.[1][2] Despite that, visitors often take samples with them, causing a disruption of the area.[2] The problem has gotten worse as tourism has increased,[2] with some visitors filling their backpacks with samples.[3][4]Шаблон:Notelist