A layer rich in magnetite has been found at Munkholmen near Trondheim. The magnetite layer occurs together with blue magnetite bearing quartzite (<>) in a greenstone, with pillow structure, of the Støren-Bymark-Group. These blue quartzites are quite common in the greenstones of the Støren-Bymark-Group and the Munkholmen occurrence is one of these. Magnetite layers associated with the blue quartzites are not that common, but are found on several localities, such as Øvre Kvam near Snåsavann.