Déodat de Dolomieu


Déodat de Dolomieu is not a caver, but a famous geologist. He discovered the chemical difference between normal limestone and dolomite, which is rather important for karst areas. To his honor the rock was called dolomite, and the part of the Alps, where he discovered the difference, and which consist of dolomite, are today called Dolomites.

Dieudonnè Sylvain Guy Tancrède de Gratet de Dolomieu was born 23. June 1750 in Dolomieu, Dauphiné, between Lyons and Chambéry. He was the ninth child of the local Lord. Dieudonnè was later latinized into Déodat.

After a journey to Malta and a military career he devoted his life to geology in 1774 at the age of 24. He traveled to the mines of Brittany, the Pyrenees, Portugal and Italy, where he spent many years. He stayed in Rome, visited the italian volcanoes and the results of the 1784 earthquake in Calabria.

When he travelled to Innsbruck in 1788/89 across the Brenner Pass, he collected some calcareous rocks in the Valle dell'Adige in Trentino. Later in France he discovered what is now named after him: the chemical difference of this rock to normal limestone.

Dolomite is a double carbonate of calcium and magnesium. This means, it consists of two different carbonate with similar chemical characteristics:

chemical name chemical formula geologic name
calcium carbonate CaCO3 limestone
calcium magnesium carbonate CaMg(CO3)2 dolomite
magnesium carbonate MgCO3 magnesite

Dolomieu wrote several books about his travels and the volcanoes in Italy.