Secondary Mineral

Mineral that forms through processes such as weathering, and in the case of meteorites can also include pre-terrestrial alteration.

Secondary minerals in meteorites that formed during terrestrial weathering include oxides and hydroxides formed directly from metallic Fe-Ni by oxidation, phosphates formed by the alteration of schreibersite, and sulfates formed by alteration of troilite. For example, surveys of iron meteorites have revealed that secondary minerals that formed by terrestrial weathering include1:

  1. Oxides and hydroxides formed directly from metallic Fe-Ni by oxidation and the incorporation of H2O, CI and, in the case of zaratite, CO32- from the terrestrial environment (CI-bearing akaganeite, bunsenite, goethite, hematite, hibbingite, lepidocrocite, maghemite, magnetite, trevorite, and, perhaps, zaratite)
  2. Graphite and kamacite formed by the decomposition of iron carbide (either cohenite or haxonite)
  3. Phosphates formed from schreibersite (apatite, arupite, cassidyite, collinsite, lipscombite, vivianite)
  4. Sulfates formed by weathering of troilite (honessite, jarosite). Additional phases in irons that formed by terrestrial alteration include metallic Cu, opal, several sulfides (pentlandite, bornite, chalcopyrite, heazlewoodite, isocubanite), at least two carbonates (reevesite, siderite), a Ni-rich phyllosilicate (pecoraite) and elemental S