Chamosite
An iron-rich chlorite, a sheet silicate found in some altered chondrites.
Key facts
- Formula
- (Fe,Mg,Al)6(Si,Al)4O10(OH)8
- Family
- Silicates
- Crystal system
- Monoclinic
What it is
Chamosite is the iron-rich member of the chlorite group, sheet silicates with an extra layer of metal hydroxide between the silicate layers. It is named after Chamoson in Switzerland. Chlorites form when rocks are altered by warm water.
Where it is found
Chlorite-group minerals, including chamosite, occur in some altered carbonaceous chondrites, in the alteration zones of chondrules, and in a few ordinary chondrites that interacted with fluid. They are much rarer than serpentine and saponite.
How it is recognised
It is green under the microscope. In meteorites it is identified by electron microscopy and its layer spacing of about 1.4 nanometres.
Did you know?
Chlorite gives many slates and schists on Earth their green colour.
Its name has nothing to do with the element chlorine; both come from the Greek word for green.