Strange Disc Is Modified Calcium Carbonate Concretion

Compare the disc from Stensö to these “fairy stone” calcium carbonate concretions from the Harricana River in the Abitibi-Témiscamingue admin region, Quebec, Canada. The Stensö piece has been sanded smooth and flat on one side. Locally these things are known as marlekor or mallrikor.



Thanks to project advisor Lotta Feldt of the Östergötland County Museum for setting me on the right track.