Bassanite
Calcium sulphate with a little water, found on Mars and in some meteorites.
Key facts
- Formula
- CaSO4·0.5H2O
- Family
- Carbonates, sulphates, salts and weathering products
- Crystal system
- Monoclinic
What it is
Bassanite is calcium sulphate with half a water molecule per formula unit, between anhydrite and gypsum. It is the mineral form of plaster of Paris. It is named after Francesco Bassani, an Italian palaeontologist.
Where it is found
Bassanite has been found in veins on Mars by the Curiosity rover and mapped from orbit. In meteorites, calcium sulphate is mostly gypsum, much of it grown after the fall, and bassanite can form when gypsum dries out.
How it is recognised
It is identified by X-ray diffraction or Raman spectroscopy, as it looks like other sulphates.
Did you know?
Did you know?
Plaster of Paris sets by turning bassanite back into gypsum.
Did you know?
Bright veins of calcium sulphate cross many Martian rocks.