Mineral Factbook

Pyrrhotite

Fe7S8IMA symbol: Pyhgrandfathered

Pyrrhotite is a sulfide or sulfosalt mineral with the formula Fe7S8, crystallizing in the hexagonal system. It has a Mohs hardness of 3.5-4.5, typically red or yellow in color, with a metallic luster, a specific gravity of 4.58-4.64. Its streak is black or gray.

Photos

Pyrrhotite specimen photo
HolDu · CC BY-SA 3.0 de · Commons
Pyrrhotite specimen photo
Parent Géry · CC BY-SA 3.0 · Commons
Pyrrhotite specimen photo
Darla Sondrol · CC0 · Commons
Pyrrhotite specimen photo
Ronald Werner · CC BY-SA 4.0 · Commons

Crystallography

Crystal systemhexagonal crystal systemWikidata (CC0)
Space groupP 1 21 1
Cell (Å, °)a = 6.8984, b = 28.695, c = 6.8915; α = 90, β = 119.956, γ = 90
Cell volume1181.93 ų, Z = 8
Axial ratios0.2404:1:0.2402calculated from COD 9016892
Source structureCOD 9016892 (American Mineralogist, 2012) — 1 of 11 structures

Powder X-ray diffraction (calculated)

2θ (degrees, Cu Kα1)I/I₀ (max 100)
d (Å)2.0692.0692.072.9882.9852.985
I/I₀10099.898.841.340.840.6

xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9016892; idealized occupancies, no preferred orientation.

Physical properties

Density (calculated)4.633 g/cm³calculated from COD 9016892
Hardness (Mohs)
4single sourceWikidata (CC0)
3.5-4.5single sourceDana, System of Mineralogy, 6th ed. (1892)
Specific gravity
4.58-4.64 g/cm3corroboratedDana, System of Mineralogy, 6th ed. (1892)
Color
red, yellowsingle sourceDana, System of Mineralogy, 6th ed. (1892)
Streak
blacksingle sourceWikidata (CC0)
black, graysingle sourceDana, System of Mineralogy, 6th ed. (1892)
Luster
metallicsingle sourceDana, System of Mineralogy, 6th ed. (1892)

Chemistry (calculated)

Molecular weight647.43 g/molcalculated from the IMA formula
Composition (wt%)Fe 60.38%, S 39.62%

Classification

Nickel-Strunz (10th)2.CC.10Wikidata (CC0)
Nickel-Strunz (9th)2.CC.10Wikidata (CC0)
Dana (8th)2.8.10.1Wikidata (CC0)