Mineral Factbook

Cordierite

Mg2Al4Si5O18IMA symbol: Crdgrandfathered

Cordierite is a silicate mineral with the formula Mg2Al4Si5O18, crystallizing in the orthorhombic system. It has a Mohs hardness of 7-7.5, typically blue or smoky in color, with a vitreous luster, a specific gravity of 2.6-2.66. Its streak is white.

Photos

Cordierite specimen photo
Kaethe17 · CC BY-SA 4.0 · Commons
Cordierite specimen photo
Reinhard Kraasch · CC BY-SA 4.0 · Commons
Cordierite specimen photo
Reinhard Kraasch · CC BY-SA 4.0 · Commons
Cordierite specimen photo
Pumber · CC BY-SA 3.0 · Commons

Crystallography

Crystal systemorthorhombic crystal systemWikidata (CC0)
Space groupC c c m
Cell (Å, °)a = 17.0046, b = 9.73133, c = 9.31989; α = 90, β = 90, γ = 90
Cell volume1542.23 ų, Z = 4
Axial ratios1.7474:1:0.9577calculated from COD 9015384
Source structureCOD 9015384 (European Journal of Mineralogy, 2010) — 1 of 50 structures

Powder X-ray diffraction (calculated)

2θ (degrees, Cu Kα1)I/I₀ (max 100)
d (Å)8.4463.1294.088.5023.3763.035
I/I₀10067.761.360.759.244.5

xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9015384; idealized occupancies, no preferred orientation.

Physical properties

Density (calculated)2.613 g/cm³calculated from COD 9015384
Hardness (Mohs)
7-7.5single sourceDana, System of Mineralogy, 6th ed. (1892)
Specific gravity
2.6-2.66 g/cm3corroboratedDana, System of Mineralogy, 6th ed. (1892)
Color
blue, smokysingle sourceDana, System of Mineralogy, 6th ed. (1892)
Streak
whitesingle sourceWikidata (CC0)
Luster
vitreoussingle sourceDana, System of Mineralogy, 6th ed. (1892)

Chemistry (calculated)

Molecular weight584.95 g/molcalculated from the IMA formula
Composition (wt%)Mg 8.31%, Al 18.45%, Si 24.01%, O 49.23%

Classification

Nickel-Strunz (10th)9.CJ.10Wikidata (CC0)
Nickel-Strunz (9th)9.CJ.10Wikidata (CC0)