Thomson had decided prior to 1804 to treat a Krasnojarsk meteorite with nitric acid with the purpose of removing the dull oxidation patina. Shortly after the contact of the metal with acid he noticed on the surface strange never seen before figures, which he detailed as described above. At the time Thomson was working in Naples, in the south of Italy. Due civil wars and great political instability, he was having serious problems to keep in contact with his colleagues in England. In this period he referred for example of the miscarring of an important letter due the murder of its carrier. Probably due these problems, he published his findings in 1804 only in French on the Bibliothèque Britannique. At the beginning of 1806, after the Battle of Campo Tenese, Napoleon invaded the Kingdom of Naples (the second French invasion in 7 years), so Thomson was again forced to flee to Sicily. In November 1806 he died at Palermo at the age of 46. In 1808 Thomson's work was again published posthumously in Italian language (translated from the original English manuscript) in Atti dell'Accademia Delle Scienze di Siena. His peregrinations across Europe and Napoleonic wars obstacled his contacts with the scientific community and this, along with his early death, obscured his contributions for many years.
In 1808 Widmanstätten independently discovered the same pattern by flame heating some iron meteorites: the different iron alloys of meteorites oxidized at different rates during heating, causing colour and lustre zone differentiation. He did not publish his discovery, but claimed it only via oral communication with his colleagues. Nevertheless, he was acknowledged by Carl von Schreibers, director of the Vienna Mineral and Zoology Cabinet, who promptly named the structure after Widmanstätten.
The full credit of the discovery should be assigned to Thomson due chronological priority of publication.
Moreover, due the discover priority of G. Thomson, several authors suggested to call these figures Thomson structure or Thomson-Widmanstätten structure.
Octahedrite meteorites have a nickel content intermediate between the norm for kamacite and taenite, which under slow cooling conditions leads to a separation of the nickel into the interleaving bands. The crystalline patterns become visible when the meteorites are cut, polished, and acid etched, because taenite is resistant to the acid.
The dimension of kamacite lamellæ ranges from coarsest to finest as the nickel content increases. Today iron meteorites are classified using the chemical classification, but originally they were classified measuring the width of these bands. It was called structural classification. Octahedrites can be divided in:
Iron meteorites without Widmanstätten bands:
Cutting the meteorite along different planes affects the shape and direction of Widmanstätten figures because kamacite lamellæ in octahedrites are precisely arranged. Octahedrites derive their name from the crystal structure paralleling an octahedron. Opposite faces are parallel so, although an octahedron has 8 faces, there are only 4 sets of kamacite plates. Iron and nickel-iron only form crystals with an external octahedral form very rarely, but these crystallographic orientations are still well defined without the external habit. Cutting an octahedrite meteorite along different planes (or any other material with octahedral symmetry, which is a sub-class of cubic symmetry) will result in one of these cases: