View source for Origin of Mars and its Elemental Composition

The sun and its planets are thought to have originated from a nebula of gas and dust referred to as the solar nebula.<ref>McGRAW-HILL ENCYCLOPEDIA OF Science & Technology, 8th Edition, (c)1997, volume 16, page 682</ref>  The gas was hydrogen and helium which formed about 98% of the mass.  The 2% of other elements formed the dust grains that eventually formed the planets.  The stellar core of the sun should have formed in on the order of 300,000 years.  A disk of dust grains rotating about the protosun coagulated into kilometer sized planetesimal in about another 10,000 years.  These bodies in turn accumulated into planets in another 10 to 100 million years in a process that mixed planetesimals from neighboring regions of the rotating disk.  
 
Since [[Mars]] and Earth formed from the dust in a single nebula from dust grains that formed at not greatly different distances form the proto sun and since planetesimals from neighboring regions mixed in forming these planets, the elemental compositions of Mars and Earth should be similar.  Mars started further from the sun, so it may have formed with a slightly richer mix of volatile elements such as methane and water ice.

Analysis of meteorites known to come from Mars and measurements of elemental composition from probes sent to Mars give us the primary information about the elemental composition of Mars but where these data are incomplete, we can be guided by expectation that the elemental composition of Mars is not very different from that of Earth.  For example [[Fluorine]] has not been discovered in any of its principal ores on Mars, but it is the 13th most abundant element on Earth forming 625 parts per million of the Earth's crust.<ref>CRC HANDBOOK of CHEMISTRY and PHYSICS, 64th EDITION (C) 1983, page F-151.</ref>  If the principal ores are not discovered on Mars, it should still be recoverable from other minerals in which it is widely distributed as a minority constituent.<ref>CRC HANDBOOK of CHEMISTRY and PHYSICS, 64th EDITION (C) 1983, page B-14</ref>

See [[Radioactive rarity on Mars]] for a discussion about if radioactive are rarer on Mars than Earth.
 
See [[Areomorphology]]
 
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[[Category:Geologic Processes]]