Sodalite
A chlorine-bearing sodium aluminium silicate formed by alteration in the CAIs of CV chondrites.
Key facts
- Formula
- Na4(Al3Si3O12)Cl
- Family
- Silicates
- Crystal system
- Cubic
What it is
Sodalite is a feldspathoid with a cage-like framework that traps chlorine. It forms where sodium and chlorine-bearing fluids react with aluminium-rich rock.
Where it is found
In Allende and other CV chondrites, sodalite occurs with nepheline in altered parts of CAIs. Because it holds chlorine, it has been used to look for the decay products of the short-lived isotope chlorine-36, which bears on when the alteration happened.
How it is recognised
It is colourless in meteorites and very fine-grained. Electron microscope analyses showing sodium, aluminium, silicon and chlorine identify it.
Did you know?
On Earth, deep blue sodalite is carved into ornaments.
Sodalite is one of the few silicates in meteorites that contains chlorine.