1.9" Marcasite Crystal Stalactites with Calcite- Linwood Mine, Iowa

The Linwood Mine has been in operation since 1944: to this day, it ranks as one of the largest limestone mining locations in the United States. On relatively rare occasions, a vug containing minerals will be opened in the mining process, which are then extracted and saved. These vugs often contain beautiful crystal aggregations of calcite, barite, and marcasite, some of which are considered world-class quality specimens.

Marcasite is an iron sulfide mineral with the chemical formula FeS2. It is similar to pyrite in both its chemical composition and appearance, but it forms an entirely different crystal structure and is much more reactive to humidity. It is often found within sedimentary rock and hydrothermal deposits, and at one point was used for its sulfur content.