Stöfflerite
Calcium feldspar in the dense hollandite structure: the high-pressure partner of anorthite.
Key facts
- Formula
- CaAl2Si2O8
- Family
- High-pressure minerals
- Crystal system
- Tetragonal
- First described
- the Martian meteorite Northwest Africa 856, 2017
Stöfflerite was approved as a new mineral in 2017 from Northwest Africa 856, a Martian shergottite found in Morocco. It is named after Dieter Stöffler, a German scientist who devised the shock-stage scale used for meteorites. It has also been found in other shocked meteorites.
What it is
Stöfflerite has the composition of anorthite, the calcium plagioclase, but the tunnel-like hollandite structure. It is the calcium member of a family of high-pressure feldspars that includes lingunite, the sodium form, and liebermannite, the potassium form.
Where it is found
It was found in shock-melt pockets in the Martian meteorite NWA 856, where plagioclase was melted and recrystallised under high pressure. It has since been reported from lunar and other shocked meteorites.
How it is recognised
It is found with the electron microprobe and confirmed by electron backscatter diffraction or Raman spectroscopy.
Did you know?
Stöffler's shock scale, from S1 to S6, is printed on the classification of almost every meteorite.
Most plagioclase in shocked meteorites turns to maskelynite glass instead of crystals like this.