Surely, quite a few people would love to own a Martian gemstone tiara? While it would certainly make for a great conversation piece, it is unlikely anyone will be adorning their head with such a jewel anytime soon. And the issue isn’t a lack of minerals on the Red Planet. Over the last decade, it has become clear that Mars is home to many “chemical” gemstones—rubies, opals, sapphires, and garnets—though they may not look exactly like their Earth-bound counterparts.
The valuable minerals discovered on Mars tend to be small, with many being microscopic. Although their elemental building blocks appear to be quite common, the minerals themselves are generally rare and likely formed under conditions vastly different from those on Earth.
So, don’t expect to stumble upon a massive sapphire while strolling across the Martian surface. Nevertheless, within—or perhaps even inside—these gemstones, we might find something far more valuable: evidence of ancient life.
Just recently, researchers reported the first-ever discovery of garnets in a Martian meteorite. That is exciting, not only because garnets are beautiful stones, but because geologists prize them for a specific reason.
Garnets serve as excellent geobarometers and geothermometers. This means they record the pressure and temperature conditions present during their formation—information that is crucial for understanding the origins of these rocks and the environmental conditions on Mars.
One possibility, however, is that this particular garnet did not originate on Mars. While Martian meteorites are indeed rocks from Mars, an impact event is required to dislodge them and launch them into space. It would be a shame—though interesting for other reasons—if this garnet had formed in space and become embedded in the Martian meteorite during its flight.
Two other possibilities are far more intriguing. One is that the Martian garnet formed from rock melted under conditions of high pressure and temperature. Garnets are associated with metamorphic rocks.
On Earth, plate tectonics gives us an abundance of metamorphic rocks. While there is no evidence of plate tectonics on Mars, such rocks could potentially have formed through a different process.
Another possibility is that the garnet formed as a result of an asteroid impact. The high pressure and temperature generated by the impact created the right conditions for the garnet to form. The research team is currently investigating this possibility.
“These results add a striking new dimension to our understanding of Martian geology and open an exciting new window into the evolution of our planetary neighbor,” explained study co-author James Darling of the University of Portsmouth.
At a recent Lunar and Planetary Science Conference, researchers presented data from NASA’s Perseverance rover indicating the possible presence of corundum on Mars. Corundum is an aluminum oxide mineral—the second-hardest naturally occurring substance on Earth after diamond. Rubies and sapphires are varieties of corundum.
The study results, currently awaiting peer review, indicate the presence of a small, pebble-sized piece of corundum. While it certainly bears no resemblance to the rubies or sapphires we are familiar with, it offers a fascinating clue regarding Martian geology. Like garnets, rubies and sapphires require high-energy, high-pressure environments to form. Jewelers might have better luck when it comes to opals. They have been detected by both NASA’s Curiosity and Perseverance rovers—meaning in two different locations on Mars. Additionally, they were found in the Martian meteorite Nakhla back in 2015.
They closely resembled fire opals. Given that opals form in the presence of subsurface water, they could be prime targets in the search for evidence of ancient life.
“The fragment of the Nakhla meteorite we have is small, and the amount of fire opal found within it is even smaller, but our discovery of the opal is highly significant,” stated Professor Martin Lee, the study’s lead author, at the time. “If Martian microbes existed, they might have been preserved in opal deposits on the Martian surface.”
When it comes to Mars, the most valuable rock isn’t a gemstone at all; it is a sample from Cheyava Falls. It represents the most compelling evidence that biological processes may have occurred on Mars.
To confirm this, we need to analyze the sample collected by the Perseverance rover here on Earth. Unfortunately, the Trump administration cancelled the Mars Sample Return mission, supposed to deliver this sample, and the future of all the Martian samples collected by Perseverance is now uncertain.
We cannot simply hop in a vehicle and go fetch it, no matter how important it may be (besides, the round trip would take at least 130 years), but at least we know where it is: safe and priceless at the edge of Jezero Crater.
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