Aphthitalite
K3Na(SO4)2IMA symbol: Attgrandfathered
Aphthitalite is a sulfate mineral with the formula K3Na(SO4)2, crystallizing in the trigonal system. It has a Mohs hardness of 3-3.5, typically white, blue or green in color, with a resinous or vitreous luster, a specific gravity of 2.63-2.656. Cleavage is distinct or imperfect.
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Crystallography
| Crystal system | trigonal crystal systemWikidata (CC0) |
|---|---|
| Space group | P -3 m 1 |
| Cell (Å, °) | a = 5.6801, b = 5.6801, c = 7.309; α = 90, β = 90, γ = 120 |
| Cell volume | 204.221 ų, Z = 1 |
| Axial ratios | 1.0000:1:1.2868calculated from COD 9007639 |
| Source structure | COD 9007639 (Acta Crystallographica, Section B, 1980) — 1 of 2 structures |
Powder X-ray diffraction (calculated)
| d (Å) | 2.84 | 2.934 | 2.04 | 4.081 | 1.42 | 3.655 |
|---|---|---|---|---|---|---|
| I/I₀ | 100 | 66.4 | 50.3 | 20.2 | 17.4 | 15.8 |
xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9007639; idealized occupancies, no preferred orientation.
Physical properties
| Density (calculated) | 2.703 g/cm³calculated from COD 9007639 |
|---|---|
| Hardness (Mohs) | 3single sourceWikidata (CC0) 3-3.5single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Specific gravity | 2.63-2.656 g/cm3corroboratedDana, System of Mineralogy, 6th ed. (1892) |
| Color | blue, green, whitesingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Luster | resinous, vitreoussingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Cleavage | distinct, imperfectDana, System of Mineralogy, 6th ed. (1892) |
Chemistry (calculated)
| Molecular weight | 332.41 g/molcalculated from the IMA formula |
|---|---|
| Composition (wt%) | K 35.29%, Na 6.92%, S 19.29%, O 38.51% |
Classification
| Nickel-Strunz (10th) | 7.AC.35Wikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 7.AC.35Wikidata (CC0) |
| Dana (8th) | 28.2.2.1Wikidata (CC0) |