Marcasite

General Information and Physical Properties of Marcasite

• Marcasite is a sulfide mineral with the chemical formula FeS.
• It has an orthorhombic crystal structure and belongs to the Strunz classification 2.EB.10a.
• The crystal habit of marcasite is typically tabular on {010}, with curved faces common.
• It exhibits cleavage on {101} and {110} planes.
• Marcasite has a metallic luster and a dark-grey to black streak.
• Crystalline structure
• Metallic luster
• Hardness of 6 to 6.5 on Mohs scale
• Brittle nature
• Pale yellow to bronze color

Occurrence of Marcasite

• Marcasite can be formed as both a primary and a secondary mineral.
• It is commonly found in sedimentary rocks such as shales, limestones, and low-grade coals.
• It also occurs in low-temperature hydrothermal veins.
• Associated minerals include pyrite, pyrrhotite, galena, sphalerite, fluorite, dolomite, and calcite.
• In sedimentary rocks, marcasite can form nodules, concretions, and crystals.
• Found in sedimentary rocks
• Commonly associated with coal deposits
• Occurs in hydrothermal veins
• Found in organic-rich environments
• Often found in shale and limestone

Uses and Applications of Marcasite

• Jewelry and decorative purposes
• Industrial applications as a catalyst
• Historical use as a substitute for pyrite
• Used in traditional medicine for its healing properties
• Utilized in the production of sulfuric acid

Formation and Decay of Marcasite

• Forms through the process of hydrothermal activity
• Occurs in low-temperature environments
• Result of the reaction between iron and sulfur
• Precipitates from groundwater solutions
• Forms in voids and fractures within rocks
• Marcasite reacts more readily than pyrite under conditions of high humidity.
• The disintegration of marcasite results in the formation of iron(II) sulfate and sulfuric acid.
• The product of marcasite decay is a white powder called melanterite.
• This decay process can damage other sulfide minerals and mineral labels.
• Storage conditions with low humidity can prevent or slow down marcasite decay.

Comparison between Marcasite and Pyrite

• Marcasite has a lower hardness compared to pyrite.
• Marcasite is more brittle and prone to decay.
• Pyrite has a golden-yellow color, while marcasite is paler.
• Marcasite is less common than pyrite in nature.
• Pyrite is more stable and less likely to oxidize than marcasite.

Marcasite Data Sources