Key points
- Jarosite is a potassium iron sulfate mineral, often found in acid mine drainage environments, oxidised ore bodies, and even on Mars.
- It plays a crucial role in controlling the mobility of toxic metals like lead, arsenic, and antimony in mine waste systems.
- Jarosite formation is a signal of extreme geochemical conditions and a clue to unlocking complex environmental and planetary processes.
Jarosite might not sparkle like a gem, but in the world of environmental geochemistry, it’s a treasure.
For me, it’s more than just a mineral. It’s a storyteller. It captures and records the history of acidic environments, offering insight into past conditions, present risks, and future opportunities to clean-up contaminants.
Jarosite: a messenger from harsh environments
Jarosite is a dusty yellow mineral you might see crusting the surface of mine tailings or dried-out wetlands.
It forms in highly acidic soils, when iron, sulfate and potassium or sodium, come together under acidic, oxidising conditions.
These conditions are common in mine waste sites. Known as acid mine drainage (AMD), sulfide minerals react with air and water, creating highly acidic water loaded with heavy metals.
In these harsh settings, jarosite starts to crystallise, forming hard, yellowish crusts on the surface of mine tailings.
At first, I saw it as just another mineral. But as I dug deeper, it became clear. Jarosite is far more than a passive bystander.
Cleaning up environmental contaminants
Jarosite has a hidden power. It can trap toxic metals like arsenic, lead and antimony inside its structure.
But, locking up toxic metals isn’t always permanent. If the environment changes, like a rise in pH or drop in oxygen, jarosite can dissolve or transform, potentially releasing contaminants back into the environment.
That makes it both a threat and an opportunity. And that’s where my research comes in.
Jarosite used to treat acid mine drainage
What started as a scientific curiosity has turned into a passion for understanding how this mineral can help us clean up environmental damage, decode complex geochemical histories and even peek into the past of another planet.
I’ve been investigating ways to stabilise or transform jarosite to hold on to contaminants more securely.
One promising approach involves a reduced form of iron we call Fe(II).
Under the right conditions, Fe(II) causes a transformation from jarosite into more stable minerals, like goethite or hematite. These new minerals are less likely to release the toxic metals, offering an environmentally effective solution for managing contaminated soils and mine waste.
We’ve been designing lab experiments to mimic these transformations and working with partners in Europe to develop column systems that could be used in the field.
It’s exciting to see how a small shift in redox chemistry could one day make a big difference in environmental remediation.
Famous on Mars
When NASA’s Opportunity rover detected jarosite on the surface of Mars, global interest in this humble mineral peaked.
Its presence tells us a lot about the red planet’s past. It tells us Mars once had acidic, iron-rich water, just like the environments we study on Earth.
Jarosite teaches us about the interplay between geochemistry, mineralogy and planetary evolution.
Whether on a tailings dam in Australia or a Martian crater, this unassuming yellow mineral tells a rich story about extreme conditions, chemical resilience and environmental transformation.
So yes, while it may not win any beauty contests, jarosite has earned its place as one of my favourite minerals. It reflects the kind of science I love. Deep, interdisciplinary and full of surprises.