Turquoise
CuAl6(PO4)4(OH)8·4H2OIMA symbol: Tquapproved
Turquoise is a phosphate, arsenate, or vanadate mineral with the formula CuAl6(PO4)4(OH)8·4H2O, crystallizing in the triclinic system. It has a Mohs hardness of 6, typically blue, gray or green in color, with a waxy luster, a calculated density of 2.927 g/cm3. Its streak is white or green.
Photos
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Crystallography
| Crystal system | triclinic crystal systemWikidata (CC0) |
|---|---|
| Space group | P -1 |
| Cell (Å, °) | a = 7.424, b = 7.629, c = 9.91; α = 68.61, β = 69.71, γ = 65.08 |
| Cell volume | 461.4 ų, Z = 1 |
| Axial ratios | 0.9731:1:1.2990calculated from COD 5000101 |
| Source structure | COD 5000101 (Zeitschrift fuer Kristallographie, Kristallgeometrie, Kristallphysik, Kristallchemie (-144,1977), 1965) — 1 of 3 structures |
Powder X-ray diffraction (calculated)
| d (Å) | 3.67 | 2.901 | 6.166 | 3.437 | 2.02 | 2.896 |
|---|---|---|---|---|---|---|
| I/I₀ | 100 | 67.4 | 46.1 | 43 | 29.6 | 28.8 |
xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 5000101; idealized occupancies, no preferred orientation.
Physical properties
| Density (calculated) | 2.927 g/cm³calculated from COD 5000101 |
|---|---|
| Hardness (Mohs) | 6single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Color | blue, gray, greensingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Streak | green, whitesingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Luster | waxysingle sourceDana, System of Mineralogy, 6th ed. (1892) |
Chemistry (calculated)
| Molecular weight | 813.44 g/molcalculated from the IMA formula |
|---|---|
| Composition (wt%) | Cu 7.81%, Al 19.9%, P 15.23%, O 55.07%, H 1.98% |
Classification
| Nickel-Strunz (10th) | 8.DD.15Wikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 8.DD.15Wikidata (CC0) |
| Dana (8th) | 42.9.3.1Wikidata (CC0) |