Fremrinamur is a high temperature area on the shield volcano Ketildyngja, just east of Mt Blafjall in the Odadahraun Area, about 25 km from the hamlet Reykjahlid on Lake Myvatn.  Sulphur was quarried there well into the 19^th century and shipped to Denmark, where was used for gunpowder.

The transport to the village Husavik, from where it was shipped, took about 4˝ days both ways.  There are several sulphur quarries in the district, but nowhere as clean as in Fremrinamur.  The main quarrying took place just east of the volcano’s main crater and inside it as well.  All such quarries in the district are now the property of the state.