Zagamiite
A dense calcium aluminium silicate that crystallised from shock melt in Martian meteorites.
Key facts
- Formula
- CaAl2Si3.5O11
- Family
- High-pressure minerals
- Crystal system
- Hexagonal
- First described
- the Zagami Martian meteorite, 2015
Zagamiite was approved as a new mineral in 2015 from the Zagami shergottite, and is named after the meteorite. It has since been found in other shocked Martian meteorites.
What it is
Zagamiite is a calcium–aluminium silicate with a hexagonal structure known from high-pressure experiments, in which much of the aluminium and silicon is surrounded by six oxygen atoms. It is not a squeezed version of any one mineral but grew from melt of plagioclase and pyroxene composition while the pressure remained high.
Where it is found
It occurs in shock-melt pockets in the Zagami shergottite and in some other Martian meteorites, where it grew as tiny elongated crystals with stishovite and other dense phases.
How it is recognised
It is identified with the electron microprobe and electron backscatter diffraction in polished sections.
Did you know?
Zagamiite is one of the few minerals named after a meteorite rather than a person or place on Earth.
Its presence shows that parts of Zagami were melted and held under very high pressure for a moment.