Skarn

Part of speech: noun

Definitions

1. A type of metamorphic rock formed by chemical alteration and contact with igneous intrusions, characterized by coarse-grained calc-silicate minerals from limestone or dolomite
2. A metamorphosed mineralogical assemblage produced by metasomatism at the boundary where magma meets carbonate sedimentary rocks, usually rich in calcium and iron-bearing silicates
3. A distinctive contact-metamorphic rock that develops when hot magmatic fluids react with surrounding carbonate rocks, often containing valuable ore minerals and diverse silicate compositions

Etymology: Swedish miners gave this rock its name, and the word they used meant "filth." Swedish "skarn" traces back to Old Norse "skarn," and the same ancestry lies behind the English word "sharn," which means cow dung. The two are doublets, meaning they share a common root but entered English by different routes. Miners in the Swedish ore fields found the crumbly, mixed-up material that clung to their valuable deposits unappealing, so they named it for the dirt it resembled. The rock forms where hot fluids rising from cooling magma meet limestone or dolomite and chemically transform it. The result is a jumble of silicate minerals, and within it ore deposits of copper, iron, tungsten, or zinc often concentrate. The word was thus adopted for a geological feature that is usually a valuable target for mining, despite its name suggesting something worthless.

Synonyms: calc-silicate rock