Mineral Factbook

Shigaite

Mn6Al3(OH)18[Na(H2O)6](SO4)2·6H2OIMA symbol: Sgaapproved

Shigaite is a sulfate mineral with the formula Mn6Al3(OH)18[Na(H2O)6](SO4)2·6H2O, crystallizing in the trigonal system. It has a calculated density of 2.207 g/cm3.

Photos

Shigaite specimen photo
Chris857 · CC BY-SA 3.0 · Commons
Shigaite specimen photo
Robert M. Lavinsky · CC BY-SA 3.0 · Commons
Shigaite specimen photo
Robert M. Lavinsky · CC BY-SA 3.0 · Commons
Shigaite specimen photo
Robert M. Lavinsky · CC BY-SA 3.0 · Commons

Crystallography

Crystal systemtrigonal crystal systemWikidata (CC0)
Space groupR -3 :H
Cell (Å, °)a = 9.512, b = 9.512, c = 33.074; α = 90, β = 90, γ = 120
Cell volume2591.56 ų, Z = 3
Axial ratios1.0000:1:3.4771calculated from COD 9004406
Source structureCOD 9004406 (The Canadian Mineralogist, 1996)

Powder X-ray diffraction (calculated)

2θ (degrees, Cu Kα1)I/I₀ (max 100)
d (Å)11.0255.5123.6752.4581.9452.2
I/I₀10029.123.123.116.314.9

xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9004406; idealized occupancies, no preferred orientation.

Physical properties

Density (calculated)2.207 g/cm³calculated from COD 9004406

Chemistry (calculated)

Molecular weight1148.0 g/molcalculated from the IMA formula
Composition (wt%)Mn 28.71%, Al 7.05%, O 52.96%, H 3.69%, Na 2%, S 5.59%

Classification

Nickel-Strunz (10th)7.DD.35Wikidata (CC0)
Nickel-Strunz (9th)7.DD.35Wikidata (CC0)