where did the iron on mars come from
Mars surface color Martian dust is reddish mostly due to the spectral properties of nanophase ferric oxides (npOx) that tend to dominate in the visible spectrum. The specific npOx minerals have not been fully constrained, but nanocrystalline red hematite (α-Fe2O3) may be the volumetrically dominant one,[6] at least at the less than 100 µm sampling depth[7] of infrared remote sensors such as the Mars Express OMEGA instrument. The rest of the iron in the dust, perhaps as much as 50% of the mass, may be in titanium enriched magnetite (Fe3O4).[8] Magnetite is usually black in colour with a black streak,[9] and does not contribute to the reddish hue of dust.
Human iron metabolism These intestinal lining cells can then either store the iron as ferritin, which is accomplished by Fe3+ binding to apoferritin (in which case the iron will leave the body when the cell dies and is sloughed off into feces), or the cell can release it into the body via the only known iron exporter in mammals, ferroportin. Hephaestin, a ferroxidase that can oxidize Fe2+ to Fe3+ and is found mainly in the small intestine, helps ferroportin transfer iron across the basolateral end of the intestine cells. In contrast, ferroportin is post-translationally repressed by hepcidin, a 25-amino acid peptide hormone. The body regulates iron levels by regulating each of these steps. For instance, enterocytes synthesize more Dcytb, DMT1 and ferroportin in response to iron deficiency anemia.[10] Iron absorption from diet is enhanced in the presence of vitamin C and diminished by excess calcium, zinc, or manganese.[11][citation needed]