Blödite
A sodium magnesium sulphate that crusts the surfaces of some carbonaceous chondrites.
Key facts
- Formula
- Na2Mg(SO4)2·4H2O
- Family
- Carbonates, sulphates, salts and weathering products
- Crystal system
- Monoclinic
What it is
Blödite is a hydrated sulphate of sodium and magnesium, a water-soluble salt like epsomite. It is named after Carl August Blöde, a German chemist. On Earth it forms where salty lakes evaporate.
Where it is found
It occurs with epsomite and gypsum in the CI chondrite Orgueil, as white veins and crusts. Studies of freshly fallen CI material and of samples from Ryugu suggest that much of this salt grew on Earth, as sulphides reacted with air and moisture during the long years in museum drawers.
How it is recognised
It forms white efflorescences that dissolve in water. Its identity is confirmed by X-ray diffraction.
Did you know?
The white veins in Orgueil were once taken as proof of water flowing inside its asteroid; now many are thought to have grown after the fall.
Ryugu samples, kept away from Earth's air, have almost none of these sulphate salts.