Rare maps
1596 Geradus Mercator Arctic Map
The north polar regions as portrayed in the 1595 atlas
https://www.raremaps.com/gallery/detail/92479/first-state-septentrionalium-terrarum-descriptio-mercator
It mentions Rapis Nigra - see Lapis Niger references
https://matriaatenaatiatifreya.blogspot.com/2025/01/asare-osiris-and-freyr.html