Marcasite FeS₂

Unit cell

Lattice constants

a = 4.436 Å, b = 5.414 Å, c = 3.381 Å; α = 90°, β = 90°, γ = 90°

Cell volume

81.2 ų

Atoms in the cell

6 (Fe 2, S 4)

Formula units Z

2

Calculated density

4.91 g cm⁻³

Shortest contact

2.212 Å

Coordination

Fe

CN 6 at 2.23 Å (6 S)

S

CN 3 at 2.23 Å (3 Fe)

About the structure

• The same FeS₂ composition and S₂²⁻ dumbbells as pyrite (also in this lab), but the FeS₆ octahedra share edges in chains along c — an orthorhombic, rutile-like arrangement instead of the cubic rock-salt-like one.
• Less stable than pyrite; forms at low temperature from acidic solutions.
• Coordinates from the Crystallography Open Database, entry 1011013 (open data); hydrogen and water sites with partial occupancy below 0.5 are left out.

Atom positions (fractional, one cell)

Z, coordination numbers, distances, density and packing on this page are computed from these coordinates.