Three-dimensional representation of the time-resolved ED-XRD patterns from the A) top detector (8.32° 2θ) and B) middle detector (5.44° 2θ). Reaction conditions: 1.25 ± 0.13 mmol mackinawite, 1.25 ± 0.13 mmol zerovalent sulfur as polysulfide (100 mol-%, theoretically complete transformation to pyrite), 200°C. Miller indices and crystal lattice distances (d-spacings) are listed in Tab. 1. Peaks used for the determination of the reaction progress variable α are marked with an asterisk (*). Weak aluminum reflections [marked with #, 2.34 Å (111), 2.02 Å (200)] were observed because of interference of the beam with the aluminum heating-block.