Editing Kamacite (section)

===Thomson structures===
{{Main article|Thomson structures}}
[[Thomson structures]], usually referred to as [[Widmanstätten patterns]], are textures often seen in meteorites that contain kamacite. These are bands which are usually alternating between kamacite and taenite. In 1804, [[William Thomson (mineralogist)|William Thomson]] stumbled upon these structures when he noticed unexpected geometric patterns after cleaning a specimen with [[nitric acid]] ({{chem|HNO|3}}). He published his observations in a French journal but due to the Napoleonic wars the English scientists, who were doing much of the meteorite research of the time, never discovered his work. It was not until 1808, four years later, that the same [[Chemical milling|etching]] patterns were discovered by Count [[Alois von Beck Widmanstätten]] who was heating iron meteorites when he noticed geometric patterns caused by the differing [[oxidation]] rates of kamacite and taenite.<ref>{{cite journal |last1=Paneth |first1=F. A. |title=The discovery and earliest reproductions of the Widmanstatten figures |journal=Geochimica et Cosmochimica Acta |year=1960 |volume=18 |issue=3 |pages=176–182 |doi=10.1016/0016-7037(60)90085-5|bibcode=1960GeCoA..18..176P }}</ref> Widmanstätten told many of his colleagues about these patterns in correspondence leading to them being referred to as Widmanstätten patterns in most literature.

Thomson structures or Widmanstätten patterns are created as the meteorite cools; at high temperatures both iron and nickel have face-centered lattices. When the meteorite is formed it starts out as entirely molten [[taenite]] (greater than 1500&nbsp;°C) and as it cools past 723&nbsp;°C the primary [[metastable]] phase of the [[alloy]] changes into taenite and kamacite begins to precipitate out. It is in this window where the meteorite is cooling below 723&nbsp;°C where the Thomson structures form and they can be greatly affected by the temperature, pressure, and composition of the meteorite.<ref name="Goldstein" />