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Martian Geology, Meteorites and the Perseverence Lander

Perseverance’s First Full-Color Look at Mars – Source: NASA

On February 18th, the most recent of NASA’s Martian exploration probes, Perseverence, landed on Mars after a seven month transit through space. An evolution of the design of the Curiosity rover which landed in 2012, Perseverence was designed with four objectives in mind: to identify environments that in the past could supported microbial life; looking for actual signs of that past microbial life; testing oxygen production from the martian atmosphere as a first step in considering how to prepare Mars for humans; and finally collecting rock and soil samples. In honor of NASA dropping yet another mechanical rock hound onto the surface of Mars, we’ve decided it’s time to briefly review Martian geology.

Perseverance’s Big Wheels , How This Mechanical Rockhound Gets Around – Source: NASA

What is known of the geology of the red planet comes from three sources: Martian meteorites that have ended up on earth, samples collected by rovers on the Martian surface, and remote measurements taken by orbiters, spacecraft, spacecraft etc. The first category, Martian meteorites finds on earth are rare but have been discovered. The oldest suspected Martian meteorite is ALH8400, an achondrite orthopyroxenite rock found in the Allan Hills of Antarctica in 1984 estimated to be around 4.1 billion years old (plus or minus a lot of years). Now housed in the Smithsonian, this meteorite was famously and controversially reported as having features resembling certain modern terrestrial bacteria in their appendages. According to Wikipedia “Orthopyroxenite is an ultramafic and ultrabasic rock that is almost exclusively made from the mineral orthopyroxene, the orthorhombic version of pyroxene and a type of pyroxenite. It can have up to a few percent of olivine and clinopyroxene.” ALH84001 is not only unique for its possible or possibly not connection to Martian life, it is also the only member of the Martian orthopyroxenite group of meteorites. Quite a feat.

Martian Meteorite ALH84001
Martian Meteorite ALH84001 – by Jstuby at English Wikipedia, CC BY-SA 3.0,

Besdies ALH84001, Martian meteorites are broadly classified as shergottites, nakhlites, chassignites and ungrouped. Most fall into the shergottites, named after the the meteor fall ar Sherghati, India in the mid 1800s. These are igneous rocks sub-classified as basaltic, olivine-phryic, or lherzolitic based crystal size and minteral content. In an attempt to be even more confusing this shergottites can also be classifed according to their rare earth content, and the two classification systems don’t line up with each other. Nakhlites, named after the fall in El-Nakhla, Egypt are igneous and rich augite fromed from basaltic magma on Mars from what is believed to be at least 4 separate volcanic eruptions approximately 1.5 billion years which spanned a 90 million year period. It is believed that the nakhlites in the very distant past were suffused with liquid water. The chassignites, named for the fall a Chassigny, Haute-Marne, Franceis a category consisting of two falls – the being found in the Western Sahara in 2000. Other than ALH8400, a number of other specimens fall into the other category, including the Kaidun meteorite fall from Yemen which may have originated on the Martian moon Phobos because Phobos has similarities to C-Type asteriods, and because the Kaidun is a carbonaceous chondrite which may contain fragments of material from the Martian surface. Needless to say, real martian meteorites are rare and valuable.

Slice of Martian shergottite meteor
Slice of Martian shergottite meteor – by Steve Jurvetson – Flickr: It came from Mars, CC BY 2.0,

The data retrieved from orbiters, spacecraft and other sensors in space on on the other are more complicated to explain and there aren’t any neat rock pictures to show, so we’ll move on to the rovers and their rock sampling. If turquoise, amethyst or malachite were discovered by the martian rovers it would rewrite the geology and history of Mars, not to mention spurring some of us Terrans to rush to Mars to begin setting up local rock shops to cater to the inevitable rock hounds who would start streaming there. But it’s an extremetly unlikely event. The Martian surface falls somewhere between basalt and andesite rocks of Earth. This means that some minerals formed similar to what is found on Earth. The presence of iron oxide gives the red rust color to the surface. Perchlorate in high percentages makes the soil highly saline, but also opens the possibility of extract water. Carbonate and phyllosilicate minerals formed when water was present in large amounts in the past.

The Jake Rock on Mars
The Jake Rock on Mars, an igneous rock found to be high in elements consistent with feldspar, such as sodium, aluminum and potassium, and lower concentrations of magnesium, iron and nickel than other such rocks previously found on Mars – By NASA/JPL-Caltech/MSSS – (direct link), Public Domain,

Among the phylosilicates present are kaolinite, monmoillonite, mica, and serprentine. Felsic minerals present inclute quartz, feldspar and maklynite. Gypsum, percholorate, ikaite, aragonite, ankerite, jarosite, olivine, pyroxene, augite, pigeonite, clinopyroxene, hematite, magnetite, and limenite are also present. Jarosite, incidently has been found on earth, rarely, usually as a result of mining waste exposed to rain and air, but also deep in the antarctic ice.

Adirondack - a Martian rock
Adirondack – a Martian rock, a hard, crystalline rock. The peaks large and small in Adirondack’s electromagnetic spectrum reveal that the minerals in the rock include olivine, pyroxene and magnetite – a common composition in volcanic basalt rocks on Earth – By NASA – NASA, Public Domain,

Of the mission seeking for life, well, that also has a geological slant. The rover is looking for something similar to a stromotolite, a material is formed from layerd microbial mats of photoshynthetic cyanobacteria that trap and bind sediment that can create a kind of living fossil. The belief is that if early microbial life existed on Mars, fossilized remains like stromotilite would be the most likely way to detect traces. While we wish Perseverence the best of luck in its search for life, our money is on its finding petrified wood – possibly Green Chromium Petrified Wood. That would be something. Not only would it rewrite Martian history as we know it, it might make that local Martian rock and crystal shop a profitable venture.

2.7 billion year old Tumbiana Stromatolite from an ancient lake environment on the souther margin of Pilbara Craton in Western Australia. – Source: NASA

We may not have any Martian meteorites in stock, but check out our selection of meteorites for sale on