Domenico Troili
The Jesuit who described the 1766 fall at Albareto in Italy, and after whom the meteorite mineral troilite is named.
Key facts
- Born
- 1722
- Died
- 1792
- Nationality
- Italian
- Field
- Jesuit priest and scholar
Domenico Troili was a Jesuit priest and teacher in northern Italy. In July 1766 a stone fell from the sky near Albareto, close to Modena, after loud explosions were heard. Troili gathered the accounts of people who had seen it and examined the stone himself.
In 1766 he published a detailed study of the fall. Looking closely at the broken stone, he noticed small, brassy grains scattered through it, which he called marchesita, an old word for metallic sulphide minerals such as pyrite. Like most scholars of his day, Troili did not think the stone came from space. He believed it had been thrown into the sky by some explosion underground and then fallen back to Earth.
Nearly a century later, the German mineralogist Gustav Rose studied the same kind of grains in meteorites and showed that they were not pyrite at all. They were a simpler iron sulphide, with one atom of sulphur for each atom of iron, a composition that is rare in Earth's crust but common in meteorites. Rose named the mineral troilite after the priest who had first described it.
Troilite is found in almost every kind of meteorite, from ordinary chondrites to irons, where it can form large rounded nodules. A sample of troilite from the Canyon Diablo iron was long used as the world's reference standard for measuring sulphur isotopes.
On the timeline
- July 1766Troili describes the Albareto stone