Déodat de Dolomieu

Déodat Gratet de Dolomieu was a French geologist born in 1750 who, during his travels through the Alps in 1791, collected samples of a curious limestone that did not fizz when treated with dilute hydrochloric acid—unusual behavior for a carbonate rock. The mineral was calcium magnesium carbonate, and in 1792, Nicolas-Théodore de Saussure named it dolomite in Dolomieu's honor.

Dolomieu's life was as dramatic as the mountains that bear his name. A Knight of Malta, he killed a fellow knight in a duel at age eighteen, was sentenced to death, pardoned, and became one of the most traveled geologists of his era. He accompanied Napoleon to Egypt in 1798 but was imprisoned in Messina for twenty-one months on his return voyage when his ship was captured. He spent his captivity writing geological treatises on scraps of paper using soot and a sharpened stick.

The Dolomite Mountains of northeastern Italy—the Dolomiti—received their name in 1864 from British geologist John Gilbert. The jagged, pale peaks, some reaching over 3,000 meters, are composed primarily of dolomite rock. They glow pink and orange at sunset, a phenomenon called enrosadira, caused by the specific way dolomite crystals interact with low-angle light.

Dolomite is used in construction, steelmaking, and as a soil conditioner. It is less common than limestone but found on every continent. The mineral, the rock, and the mountains all carry the name of a geologist who identified something new by noticing what was absent: the fizz that should have been there but was not.