Jarosite

Jarosite is a yellow-brown mineral that contains potassium, iron, and sulphate — and researchers have found it could serve as a natural geological clock on Mars.

• Recently, a team of researchers from around India sampled six jarosite veins from Kachchh in Gujarat, whose arid, salty terrain is similar to that of Mars.
• In the lab, the team analysed how much light the mineral emitted due to the energy it had stored from natural radiation, a phenomenon called luminescence.
• Jarosite is common on Mars.

(Source: TH)