Frozen fauna – Frossen fauna

It’s not gold all that glitters, reindeer do too

By Jørgen Rosvold

For some, Christmas is about sparkly stuff; sparkling decorations or sparkling jewelry. For many, Christmas is also about reindeer. Santa wouldn’t be the same without Rudolf and his flock. Snow patches have both, in one and the same: sparkling reindeer! Or at least sparkling reindeer bones.

Vivianite is an iron phosphate mineral that sometimes forms on bones and teeth in waterlogged oxygen poor environments. It is usually white or colorless, but when exposed to oxygen it will turn bright blue. To form, vivianite requires a source of both phosphate and iron. In archaeological settings, human and animal remains with vivianite is usually found in relation to manure deposits or organic waste dumps rich in phospates, in areas with iron rich soils or where the bones have lain close to iron objects.

Vivianite may form as a thin powdery layer that can cover entire bones, or it can form thick crystaline structures. The famous Blue Babe, the Alaskan bison mummy, was largely covered by this mineral. The skin of Ötzi, the ice man, was also covered with vivianite in places that had lain close to the iron rich bedrock beneath.

Only a few of the snow patch bones and antlers have so far been found with vivianite, but the conditions for its formation is good in this frozen environment with slowly decomposing carcasses and large amounts of animal dung. It is, however, still a mystery what the iron source is. Arrowheads?

Reindeer bone covered by vivianite. Something for the Christmas tree? Photo: Jørgen Rosvold, NTNU University Museum

More on vivianite:

Vivianite on Wikipedia

– McGowan & Pragnell (2006): The Significance of Vivianite in
Archaeological Settings. Geoarchaeology 21, 93-111.

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