On the Martian surface, the Perseverance rover has spotted mysterious white rocks that could reveal an ancient secret: the Red Planet might once have been drenched in rain under a tropical sky. Although their origin remains unclear, these curious stones may hold clues to a humid, possibly life-friendly world that Perseverance continues to explore, one rock at a time.
As Perseverance travels across Mars, it has encountered all sorts of rocks, each preserving a small piece of the planet’s geological or environmental history.
While every rock provides valuable information that helps scientists understand Mars’s past, a few have drawn special attention. These are the thousands of tiny white fragments Perseverance has observed along its route.
These pale stones stand out against the reddish landscape of Jezero Crater, suggesting they broke off from faraway outcrops and were carried across great distances. So far, about twenty of these whitish rocks have been analysed using Perseverance’s SuperCam and Mastcam-Z instruments.
During its journey, Perseverance has already encountered these isolated blocks of light-colored rock on numerous occasions. © Broz et al. 2025, Communications Earth and Environment
Kaolinite: a mineral revealing a tropical past
Recent findings published in Communications Earth and Environment show that some of these rocks contain kaolinite, a clay mineral rich in hydrated aluminium. On Earth, this mineral forms when aluminosilicate minerals such as feldspars break down through chemical alteration — a process that happens mainly in warm, humid environments.
Typically, this type of alteration occurs when water flows intensely through the soil, washing away soluble ions like sodium, potassium, and calcium, leaving silicon and aluminium to recombine and create kaolinite. That’s why kaolinite is most often found in tropical regions.
Kaolin is a rock primarily composed of kaolinite, a mineral typical of tropical environments on Earth. © James St. John, Wikimedia Commons, CC BY 2.0
This explains why scientists are so interested in the discovery: finding kaolinite-rich rocks on Mars could mean the planet once had a tropical climate, with heavy rainfall and perhaps even monsoons.
An origin still unknown
Although these analyses confirm that Mars once had water and humidity, many questions remain unanswered. To understand this tropical episode more precisely — and to date it within the planet’s geological history — scientists need to locate the outcrop from which these rocks originated.
So far, Perseverance has found fragments scattered across its path, but no major outcrop has been identified. According to planetary scientist Briony Horgan, these rocks might have been transported by rivers into the ancient lake that once filled Jezero Crater, or they could be debris ejected during a meteorite impact. Nothing is certain yet.
Despite these uncertainties, a picture is emerging of a Martian landscape shaped by rain over millions of years — an environment where life could potentially have developed.
Perseverance continues its journey of discovery
While the search for the source of these white rocks and possible traces of life continues, Perseverance presses on with its Martian adventure. The rover is now exploring outside Jezero Crater, having completed its climb up the crater’s rim in 2024.
Here again, new discoveries are being made. Recently, Perseverance came across an unusual rock whose texture and shape piqued researchers’ curiosity.
Phippsaksla, the strangely shaped rock recently discovered by Perseverance, could be a meteorite. © NASA, JPL-Caltech, ASU
Analyses using Mastcam-Z revealed high concentrations of iron and nickel, leading scientists to believe that this rock, named Phippsaksla, might actually be a meteorite.
Morgane Gillard
Journalist
As a child, I dreamed of being a paleontologist, an astronaut, or a writer… and ultimately, my heart led me to geology. After years of studying to gain deep knowledge, I now share it with you, the readers of Futura!
Looking back, I realize that my passion for Earth and science in general started very early! My first spelunking expedition was at the age of 4, my first scuba dive at 7, fossil hunting all across France, nighttime outings to watch the stars… With a father who was a chemistry teacher and an avid cave diver, and a mother who was the first female commercial diver in France, my childhood was filled with adventure and discovery! One memory in particular stands out: observing the Hale-Bopp comet in 1997, in the middle of the night, standing in a field while my parents whispered the countdowns for the exposure times to photograph that strange celestial object lighting up the sky. That image is forever etched in my memory, a moment filled with a certain magic—and even today, I still get chills when I gaze up at the stars. Head in the stars, feet on the ground. It was probably during our travels in an old Volkswagen van, between Andalusia and the barren lands of the North Cape, that I discovered the incredible beauty of nature and the stunning diversity of landscapes our planet has to offer.
Discovering Earth and Its Inner Workings
After high school, pursuing scientific studies felt like a natural choice, so it came as no surprise when I enrolled at university for a full degree in Earth Sciences. But I struggled to stick to just one field. During my studies, I explored all areas of geoscience: from geodesy to electromagnetism, from mineralogy to field geology… I loved learning about Earth and its complexity, its beauty, its strength, and its fragility. So when I was offered the chance to start a PhD in geodynamics in 2011—studying the development of the Australian and Antarctic margins—I didn’t hesitate. More things to learn and discover!
One of the most fascinating aspects of geosciences is how you juggle both vast timescales and spatial scales. You never stay still—you’re constantly zooming in and out. In a single day, you might shift from looking at the oceanic crust to analyzing a tiny mineral. You might be discussing tectonic plate movements and then chemical interactions between minerals. What could be more exciting?
From Continent to Ocean: The Incredible Journey of a PhD
Over those three years, I gradually specialized in seismic interpretation. Like a detective, I learned to read those striped black-and-white images and reconstruct a story—the story of plate tectonics and the opening of an ocean. Specifically, I worked on the development of detachment faults in the continent-ocean transition zone and the sedimentary record they produce. I had the opportunity to present my work at many international conferences and built a strong scientific identity. Three years of hard work, amazing discoveries, and incredible encounters shaped me into who I am today. After defending my thesis in 2014, I completed several years of postdoctoral research with CNRS and in collaboration with oil companies interested in these increasingly strategic zones for petroleum exploration.
Science, Always and Forever
But… academia is demanding, requiring full-time commitment—something not always compatible with starting a family. So I made the tough decision to shift career paths and turned to scientific writing. It turned out to be a great choice, as it allows me to keep talking about science, especially geology. Working with Futura is a real opportunity because it lets me share the world of Earth Sciences—an often-overlooked field—with a broad audience. After all, what could be more important than understanding the planet we live on?