Köttigite
Zn3(AsO4)2·8H2OIMA symbol: Kötgrandfathered
Köttigite is a phosphate, arsenate, or vanadate mineral with the formula Zn3(AsO4)2·8H2O. It has a Mohs hardness of 2.5-3, typically red in color, with a silky luster, a specific gravity of 3.1. Its streak is white or red.
Photos
Crystallography
| Space group | C 1 2/m 1 |
|---|---|
| Cell (Å, °) | a = 10.241, b = 13.405, c = 4.757; α = 90, β = 105.21, γ = 90 |
| Cell volume | 630.168 ų, Z = 2 |
| Axial ratios | 0.7640:1:0.3549calculated from COD 9000698 |
| Source structure | COD 9000698 (American Mineralogist, 1979) |
Powder X-ray diffraction (calculated)
| d (Å) | 6.703 | 3.224 | 7.954 | 2.994 | 2.734 | 3.009 |
|---|---|---|---|---|---|---|
| I/I₀ | 100 | 40.7 | 36.9 | 28.8 | 27 | 21.2 |
xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9000698; idealized occupancies, no preferred orientation.
Physical properties
| Density (calculated) | 3.258 g/cm³calculated from COD 9000698 |
|---|---|
| Hardness (Mohs) | 2.5-3single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Specific gravity | 3.1 g/cm3single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Color | redsingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Streak | red, whitesingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Luster | silkysingle sourceDana, System of Mineralogy, 6th ed. (1892) |
Chemistry (calculated)
| Molecular weight | 618.19 g/molcalculated from the IMA formula |
|---|---|
| Composition (wt%) | Zn 31.74%, As 24.24%, O 41.41%, H 2.61% |
Classification
| Nickel-Strunz (10th) | 8.CE.40Wikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 8.CE.40Wikidata (CC0) |