Properties of Marcasite
Marcasite, as a mineral, is a form of iron sulfide with the chemical formula (FeS2). It shares a similar composition with pyrite but has a different crystal structure. Marcasite crystallizes in the orthorhombic system and often forms small, brassy-yellow, metallic-looking crystals.

The following table provides a comprehensive list of marcasite properties in both SI and US customary/Imperial units at normal temperature and pressure (NTP).
Note: click on the button to switch between Metric and Imperial units.
| Physical Properties | Metric |
|---|---|
| Chemical Formula | FeS2 |
| Molar Mass | 119.979 g/mol |
| Crystal System | Orthorhombic |
| Mohs Hardness | 6 - 6.5 |
| Density | 4900 kg/m3 |
| Color | White green |
| Diaphaneity | Opaque |
| Luster | Metallic |
| Cleavage | {101} |
| Fracture | Conchoidal |
| Streak | Black |
Note: unless stated otherwise, all values are taken at room temperature (approximately 20°C or 68°F) and 1 atm pressure. (1 atm = 101,325 Pa)
References: 1) Cardarelli, François. Materials Handbook: A Concise Desktop Reference. Switzerland: Springer International Publishing, 2018. 2) CRC Handbook of Chemistry and Physics, 97th Edition. United Kingdom: CRC Press, 2016-2017.
