Cubanite
A copper iron sulphide found in CI chondrites, comet dust and samples from the asteroid Ryugu.
Key facts
- Formula
- CuFe2S3
- Family
- Sulphides
- Crystal system
- Orthorhombic
What it is
Cubanite is a sulphide with one copper atom and two iron atoms for every three of sulphur. It is named after Cuba, where it was first described. The common orthorhombic form changes structure above about 210 °C, so it acts as a thermometer.
Where it is found
It occurs with pyrrhotite and pentlandite in CI chondrites such as Orgueil and Ivuna, in samples from Ryugu, and in dust from comet Wild 2 brought back by Stardust. Its low-temperature form shows these rocks were never strongly heated after it grew.
How it is recognised
In reflected light it is pale brassy yellow and strongly anisotropic. It is confirmed by microprobe analysis or electron diffraction.
Did you know?
Cubanite in Wild 2 dust showed that comet material had been touched by liquid water.
It is one of the minerals that link CI chondrites with Ryugu.