Seifertite
The densest known natural form of silica, formed by shock in Martian meteorites.
Key facts
- Formula
- SiO2
- Family
- High-pressure minerals
- Crystal system
- Orthorhombic
- First described
- the Shergotty Martian meteorite, 2008
Seifertite was described in 2008 from the Shergotty meteorite, which fell in India in 1865. It is named after Friedrich Seifert, a German mineral physicist.
What it is
Seifertite is silicon dioxide with a structure related to the mineral scrutinyite, denser even than stishovite. In experiments on quartz it appears only above about 100 gigapascals, but in meteorites it seems to have formed from silica glass or cristobalite at lower pressures during the brief shock.
Where it is found
It occurs in silica grains in the shergottites Shergotty and Zagami from Mars, and has been reported in some lunar meteorites.
How it is recognised
It is identified with electron diffraction and X-ray methods, as tiny intergrown lamellae.
Did you know?
Seifertite is the densest form of silica known in nature.
Its formation path shows that the peak pressure in a shock is not the only thing that decides which mineral forms.