Mineral Factbook

Gehlenite

Ca2Al(SiAl)O7IMA symbol: Ghgrandfathered

Gehlenite is a silicate mineral with the formula Ca2Al(SiAl)O7, crystallizing in the tetragonal system. It has a Mohs hardness of 5.5-6, typically brown, gray or green in color, with a resinous or vitreous luster, a specific gravity of 2.9-3.07. Its streak is white or gray.

Photos

Gehlenite specimen photo
Krzątała, Arkadiusz and Krüger, Biljana and Galuskina, Irina and Vapnik, Yevgeny and Galuskin, Evgeny · CC BY 4.0 · Commons
Gehlenite specimen photo
Galuskin, E.; Galuskina, I.; Książek, M.; Kusz, J.; Vapnik, Y. · CC BY 4.0 · Commons
Gehlenite specimen photo
Sharygin, Victor V. and Yakovlev, Grigory A. and Wirth, Richard and Seryotkin, Yurii V. and Sokol, Ellina V. and Nigmatulina, Elena N. and Karmanov, Nikolai S. and Pautov, Leonid A. · CC BY 4.0 · Commons
Gehlenite specimen photo
Reinhard Kraasch · CC BY-SA 4.0 · Commons

Crystallography

Crystal systemtetragonal crystal systemWikidata (CC0)
Space groupP -4 21 m
Cell (Å, °)a = 7.685, b = 7.685, c = 5.0636; α = 90, β = 90, γ = 90
Cell volume299.1 ų, Z = 2
Axial ratios1.0000:1:0.6589calculated from COD 1000048
Source structureCOD 1000048 (Physics and Chemistry of Minerals (Germany), 1992) — 1 of 6 structures

Powder X-ray diffraction (calculated)

2θ (degrees, Cu Kα1)I/I₀ (max 100)
d (Å)2.8441.7533.0613.7052.431.374
I/I₀10026.920.917.216.614.1

xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 1000048; idealized occupancies, no preferred orientation.

Physical properties

Density (calculated)3.045 g/cm³calculated from COD 1000048
Hardness (Mohs)
5.5-6single sourceDana, System of Mineralogy, 6th ed. (1892)
Specific gravity
2.9-3.07 g/cm3corroboratedDana, System of Mineralogy, 6th ed. (1892)
Color
brown, gray, greensingle sourceDana, System of Mineralogy, 6th ed. (1892)
Streak
gray, whitesingle sourceDana, System of Mineralogy, 6th ed. (1892)
Luster
resinous, vitreoussingle sourceDana, System of Mineralogy, 6th ed. (1892)

Chemistry (calculated)

Molecular weight274.2 g/molcalculated from the IMA formula
Composition (wt%)Ca 29.23%, Al 19.68%, Si 10.24%, O 40.84%

Classification

Nickel-Strunz (10th)9.BB.10Wikidata (CC0)
Nickel-Strunz (9th)9.BB.10Wikidata (CC0)
Dana (8th)55.4.1.2Wikidata (CC0)