Mars is a terrestrial planet that consists of minerals
containing silicon and oxygen, metals, and other elements that typically make
up rock. The surface of Mars is primarily composed of tholeiitic basalt,
although parts are more silica-rich than typical basalt and may be similar to
andesitic rocks on Earth or silica glass. Regions of low albedo show
concentrations of plagioclase feldspar, with northern low albedo regions
displaying higher than normal concentrations of sheet silicates and
high-silicon glass. Parts of the southern highlands include detectable amounts
of high-calcium pyroxenes.
Localized concentrations of hematite and olivine have also been found. Much of the surface is deeply covered by finely grained iron(III) oxide dust.
Localized concentrations of hematite and olivine have also been found. Much of the surface is deeply covered by finely grained iron(III) oxide dust.
Although Mars has no evidence of a current structured global
magnetic field, observations show that parts of the planet's crust have been magnetized,
and that alternating polarity reversals of its dipole field have occurred in
the past. This paleomagnetism of magnetically susceptible minerals has
properties that are similar to the alternating bands found on the ocean floors
of Earth. One theory, published in 1999 and re-examined in October 2005 (with
the help of the Mars Global Surveyor), is that these bands demonstrate plate
During the Solar System's formation, Mars was created as the
result of a
stochastic process of run-away accretion out of the protoplanetary
disk that orbited the Sun. Mars has many distinctive chemical features caused
by its position in the Solar System. Elements with comparatively low boiling
points, such as chlorine, phosphorus, and sulphur, are much more common on Mars
than Earth; these elements were probably removed from areas closer to the Sun
by the young star's energetic solar wind.
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