Alnön, outside Sundsvall

The Volcano That Froze on Alnön

Alnön is known for its beautiful scenery, but the island carries a verified and extremely rare natural history. Some 570 million years ago the area was struck by enormous volcanic eruptions. It was not an ordinary volcano: it was a magma chamber filled with exceptionally rare, calcium-rich rock types. When geologists began to study the island they discovered the rock alkaline syenite and the unique alnöite, named after the island itself. Alnön is internationally known in geology because the special chemical composition of its magma makes the bedrock more similar to the African continent than to the rest of Scandinavia. The volcano froze. The island remembers.