Dumortierite
AlAl6BSi3O18IMA symbol: Dumredefined
Dumortierite is a silicate mineral with the formula AlAl6BSi3O18, crystallizing in the orthorhombic system. It has a Mohs hardness of 7, typically blue or green in color, with a vitreous luster, a specific gravity of 3.265-3.36. Its streak is white; cleavage is distinct or imperfect.
Photos
Crystallography
| Crystal system | orthorhombic crystal systemWikidata (CC0) |
|---|---|
| Space group | P n m a |
| Cell (Å, °) | a = 4.6901, b = 11.7874, c = 20.1872; α = 90, β = 90, γ = 90 |
| Cell volume | 1116.03 ų, Z = 4 |
| Axial ratios | 0.3979:1:1.7126calculated from COD 9014389 |
| Source structure | COD 9014389 (The Canadian Mineralogist, 2012) — 1 of 12 structures |
Powder X-ray diffraction (calculated)
| d (Å) | 5.844 | 3.222 | 2.886 | 5.894 | 3.449 | 3.06 |
|---|---|---|---|---|---|---|
| I/I₀ | 100 | 91.5 | 69.5 | 62.2 | 59.4 | 52.3 |
xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9014389; idealized occupancies, no preferred orientation.
Physical properties
| Density (calculated) | 3.377 g/cm³calculated from COD 9014389 |
|---|---|
| Hardness (Mohs) | 7single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Specific gravity | 3.265-3.36 g/cm3Dana, System of Mineralogy, 6th ed. (1892) |
| Color | blue, greensingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Streak | whitesingle sourceWikidata (CC0) |
| Luster | vitreoussingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Cleavage | distinct, imperfectDana, System of Mineralogy, 6th ed. (1892) |
Chemistry (calculated)
| Molecular weight | 571.93 g/molcalculated from the IMA formula |
|---|---|
| Composition (wt%) | Al 33.02%, B 1.89%, Si 14.73%, O 50.35% |
Classification
| Nickel-Strunz (10th) | 9.AJ.10Wikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 9.AJ.10Wikidata (CC0) |