Marcasite

Marcasite is a mineral composed primarily of iron disulfide (FeS₂) , just like pyrite. Although they have the same chemical formula, marcasite and pyrite are two different polymorphs : they have distinct crystal structures .

🔹 Main characteristics of marcasite

Characteristic Detail
Chemical formula FeS₂
Color Pale yellow to metallic white
Glow Metallic, sometimes with iridescence
Hardness (Mohs) 6 to 6.5
Density About 4.8 to 4.9
Crystallization Orthorhombic
Break Irregular to conchoidal
Alteration Unstable: degrades into sulfuric acid + iron sulfate

🔸 Differences between marcasite and pyrite

Property Marcasite Pyrite
Structure Orthorhombic Cubic
Stability Less stable, easily damaged More stable in air
Color Paler, sometimes greenish Golden, more brilliant
Shapes Blades, radial masses Cubes, pyritohedrons

💎 Uses of Marcasite

  • Jewelry : Sometimes used as ornament, especially in the 19th century (so-called "marcasite" jewelry), although it was often polished pyrite or imitations.

  • Mineralogical collections : Appreciated for its radiating or nodule crystalline forms.

  • Geology : Evidence of oxygen-poor environments in sedimentary rocks.

⚠️ Fragility and precautions

  • Unstable in air : marcasite disintegrates over time, forming a white dust (sulfuric acid and iron sulfate).

  • Storage : It must be kept dry and away from humidity.

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List of Stones & Minerals

Marcasite is a mineral that resembles pyrite. It is found in iron mines. It belongs to the orthorhombic system.

Its benefits : marcasite is the stone of inner light which radiates in inner peace.

Astrological signs : Leo, Virgo.

Chakra : Solar, coronal plexus.