William Thomson
The English mineralogist in Naples who first saw the crystal pattern inside an iron meteorite, in 1804.
Key facts
- Born
- c. 1760
- Died
- 1806
- Nationality
- British
- Field
- Mineralogist and physician
William Thomson, known in Italy as Guglielmo Thomson, was an English doctor and mineralogist who settled in Naples and studied the rocks of Vesuvius and southern Italy. He is not to be confused with the Victorian physicist William Thomson, Lord Kelvin.
In 1804 Thomson wanted to clean a piece of the Krasnojarsk iron, the great Siberian pallasite described by Peter Simon Pallas. He treated its surface with nitric acid. As the acid ate into the metal, it attacked some parts faster than others, and a geometric pattern of crossing bands appeared on the surface.
Thomson recognised that the pattern showed the metal's inner crystal structure and published a description in French that same year. His report appeared in a journal printed in Geneva, and because he died only two years later, in 1806, few people noticed it. In 1808 Alois von Beckh-Widmanstätten found the same pattern independently in Vienna, and his name became attached to it.
Historians of science have since restored Thomson's place, and some writers use the name Thomson structure. His method, acid etching of a polished surface, is the one still used to reveal the pattern in iron meteorites today. It must only be done by adults with proper protection, because the acids involved are dangerous.