A team of Indian scientists has discovered that Jarosite, a mineral commonly found on Mars, can serve as a natural luminescent clock to record geological events up to 25,000 years. The study was conducted on six Jarosite veins from Kachchh, Gujarat, under simulated Martian conditions.
What is Jarosite?
- A Yellow-brown mineral, potential natural clock on Mars
- Type: Hydrous sulfate mineral
- Formula: KFe₃(SO₄)₂(OH)₆
- Composition: Potassium, Ferric Iron (Fe³⁺), Sulfate
- Color: Dark yellow to yellow-brown
- Hardness: 2.5–3.5 (Mohs scale)
- Structure: Trigonal crystal system; brittle with basal cleavage
- Thermal stability: Retains luminescence up to 450°C, suitable for rover drills
- Lustre: Vitreous to dull; translucent to opaque
- Formation: Forms through oxidation of iron sulfides (e.g., pyrite)
- Can date: Events up to 25,000 years using luminescence response
Where is Jarosite Found?
On Earth:
- Acidic sulfate soils
- Acid mine drainage zones
- Volcanic and sedimentary rocks in arid regions
- Antarctica ice cores
- Kachchh (India) and Sierra Peña Blanca (Mexico)
On Mars:
- Detected by NASA rovers – Spirit, Opportunity, and Curiosity
- Locations: Meridiani Planum and Gale Crater
- Indicates acidic and oxidizing conditions on Mars
Why is Jarosite Important?
Natural Radiation Clock:
- Emits light (luminescence) after absorbing radiation over time
- Can record geological events up to 25,000 years old
- Useful for dating dust storms, flood deposits, volcanic ash on Mars
Ideal for Mars Rovers:
- Strong, stable, and luminescent even after heating
- Detectable with small heaters and LEDs, allowing non-destructive testing
Experiment Conducted by Indian Scientists
- Sample Site: Six jarosite veins from Kachchh, Gujarat
- Process:
- Grains washed in weak acid to enhance brightness
- Exposed to radiation and heat cycles
- Luminescence emissions observed at 100°C, 150°C, 300°C, 350°C
- Retained brightness even after heating to 450°C
- Radiation Dose Tolerance:
- Saturated between 590–2600 Gray
- On Mars, radiation = ~65 milligray/year, allowing 25,000-year dating range
Why Kachchh Was Chosen?
- Extreme aridity and salinity mimic Martian conditions
- Considered an ideal Mars analog site for testing geological and environmental responses
Applications of Jarosite
Planetary Dating Tool:
- Acts as a luminescent radiation clock for Mars surface processes
- Works with Potassium-Argon (K-Ar) dating method- Based on decay of Potassium-40 to Argon-40
Mars Missions:
- Can be integrated into Mars rover payloads
- Enables age determination without damaging samples
Environmental Indicator:
- Traces oxidation stages in both mining and glacial processes
Geological Marker:Helps detect Ice Age layers in deep Earth or planetary cores