Helgustaðanáma is an old Iceland spar mine on the property of Helgustaðir in Fjarðarbyggð which has been protected as a natural monument since 1975. Helgustaðanáma is one of the best known Iceland spar mines in the world. Iceland spar was mined there since the 16th century until the early 21st century. The English term is Iceland spar, and the crystal is named after Iceland in many other languages.

Most of the Iceland spar found in museums around the world comes from Helgustaðarnáma, and some of the biggest and clearest specimens of Iceland spar have been found in the mine. Iceland spar is a particularly transparent crystalised variety of calcite and served an important purpose in the development of various studies of the properties of light. Those studies led to important discoveries in the fields of physics, chemistry and geology in the 18th and 19th centuries. The removal of Iceland spar from the mine was common in past years but is now protected, and it is strictly forbidden to remove it.