Mars is differentiated, which—for a terrestrial planet—implies that it has a central core made up of high density matter (mainly metallic iron and nickel) surrounded by a less dense, silicate mantle and crust.

Based on these data sources, scientists think that the most abundant chemical elements in the Martian crust are silicon, oxygen, iron, magnesium, aluminium, calcium, and potassium.

On September 5, 2017, scientists reported that the Curiosity rover detected boron, an essential ingredient for life on Earth, on the planet Mars.

[18][19] On 16 December 2014, NASA reported the Curiosity rover detected a "tenfold spike", likely localized, in the amount of methane in the Martian atmosphere.

Sample measurements taken "a dozen times over 20 months" showed increases in late 2013 and early 2014, averaging "7 parts of methane per billion in the atmosphere."

[20][21] On 25 October 2023, scientists, helped by information from the InSight lander, reported that the planet Mars has a radioactive magma ocean under its crust.

Most of our current knowledge about the mineral composition of Mars comes from spectroscopic data from orbiting spacecraft, in situ analyses of rocks and soils from six landing sites, and study of the Martian meteorites.

These minerals are the primary constituents of basalt, a dark volcanic rock that also makes up the Earth's oceanic crust and the lunar maria.

The mineral olivine occurs all over the planet, but some of the largest concentrations are in Nili Fossae, an area containing Noachian-aged rocks.

However, other researchers have suggested that ST2 represents weathered basalts with thin coatings of silica glass or other secondary minerals that formed through interaction with water- or ice-bearing materials.

Both TES and the Thermal Emission Imaging System (THEMIS) on the Mars Odyssey spacecraft have identified high-silica rocks in Syrtis Major and near the southwestern rim of the crater Antoniadi.

[42][43] Using SAM's mass spectrometer, scientists measured isotopes of helium, neon, and argon that cosmic rays produce as they go through rock.

These measurements are necessary for human missions to the surface of Mars, to provide microbial survival times of any possible extant or past life, and to determine how long potential organic biosignatures can be preserved.

[41][43] The two samples, John Klein and Cumberland, contain basaltic minerals, Ca-sulfates, Fe oxide/hydroxides, Fe-sulfides, amorphous material, and trioctahedral smectites (a type of clay).

[51] A Late Noachian/EarlyHesperian or younger age indicates that clay mineral formation on Mars extended beyond Noachian time; therefore, in this location neutral pH lasted longer than previously thought.

The global predominance of dust obscures the underlying bedrock, making spectroscopic identification of primary minerals impossible from orbit over many areas of the planet.

[65] In 2010, analyses by the Mars Exploration Rover Spirit identified outcrops rich in magnesium-iron carbonate (16–34 wt%) in the Columbia Hills of Gusev crater.

The magnesium-iron carbonate most likely precipitated from carbonate-bearing solutions under hydrothermal conditions at near-neutral pH in association with volcanic activity during the Noachian Period.

They contain the minerals olivine, pyroxene, plagioclase, and magnetite, and they look like volcanic basalt as they are fine-grained with irregular holes (geologists would say they have vesicles and vugs).

[31] Plain's rocks have been very slightly altered, probably by thin films of water because they are softer and contain veins of light colored material that may be bromine compounds, as well as coatings or rinds.

One type of soil, called Paso Robles, from the Columbia Hills, may be an evaporate deposit because it contains large amounts of sulfur, phosphorus, calcium, and iron.

[79] After Spirit stopped working scientists studied old data from the Miniature Thermal Emission Spectrometer, or Mini-TES and confirmed the presence of large amounts of carbonate-rich rocks, which means that regions of the planet may have once harbored water.

On the other hand, a small amount of hematite that was present meant that there may have been liquid water for a short time in the early history of the planet.

[citation needed] Few rocks were visible on the surface where Opportunity landed, but bedrock that was exposed in craters was examined by the suite of instruments on the Rover.

Similar high levels were found by other rovers at Ares Vallis and Gusev Crater, so it has been hypothesized that the mantle of Mars may be phosphorus-rich.

Observations at the site have led scientists to believe that the area was flooded with water a number of times and was subjected to evaporation and desiccation.

On September 27, 2012, NASA scientists announced that the Curiosity rover found evidence for an ancient streambed suggesting a "vigorous flow" of water on Mars.

[52][53] On December 9, 2013, NASA reported that, based on evidence from Curiosity rover studying Aeolis Palus, Gale Crater contained an ancient freshwater lake which could have been a hospitable environment for microbial life.

Sample measurements taken "a dozen times over 20 months" showed increases in late 2013 and early 2014, averaging "7 parts of methane per billion in the atmosphere."

[20][21] In addition, high levels of organic chemicals, particularly chlorobenzene, were detected in powder drilled from one of the rocks, named "Cumberland", analyzed by the Curiosity rover.