Brearleyite
A chlorine-bearing calcium aluminate formed when fluids altered an ancient inclusion.
Key facts
- Formula
- Ca12Al14O32Cl2
- Family
- Oxides
- Crystal system
- Cubic
- First described
- the CV3 chondrite Northwest Africa 1934, 2011
Brearleyite was approved as a new mineral in 2010 and published in 2011 from a calcium-aluminium-rich inclusion in the CV3 chondrite Northwest Africa 1934. It is named after Adrian Brearley, a meteorite mineralogist who studies how water changed the earliest solids.
What it is
Brearleyite is a calcium aluminium oxide with chlorine held in cages in its cubic structure. It belongs to the mayenite family, minerals best known on Earth from altered limestone near volcanoes and from cement clinker.
Where it is found
It occurs as fine grains replacing krotite and other primary minerals in a calcium-aluminium-rich inclusion in NWA 1934. It formed later than the inclusion itself, when chlorine-bearing fluids or gases reacted with it, either in the solar nebula or on the parent asteroid.
How it is recognised
It is found with the scanning electron microscope and identified by its composition and electron backscatter diffraction.
Did you know?
Synthetic mayenite-family compounds are studied as materials that can conduct electricity like a metal.
Its chlorine shows that even the hardiest early solids were later touched by fluids.