Crandallite
CaAl3(PO4)(PO3OH)(OH)6IMA symbol: Cdlredefined
Crandallite is a phosphate, arsenate, or vanadate mineral with the formula CaAl3(PO4)(PO3OH)(OH)6, crystallizing in the trigonal system. It has a Mohs hardness of 4.5-5, typically red in color, a specific gravity of 3.2. Cleavage is imperfect or perfect.
Photos
Crystallography
| Crystal system | trigonal crystal systemWikidata (CC0) |
|---|---|
| Space group | R -3 m :H |
| Cell (Å, °) | a = 7.005, b = 7.005, c = 16.192; α = 90, β = 90, γ = 120 |
| Cell volume | 688.093 ų, Z = 3 |
| Axial ratios | 1.0000:1:2.3115calculated from COD 9000383 |
| Source structure | COD 9000383 (American Mineralogist, 1974) |
Powder X-ray diffraction (calculated)
| d (Å) | 2.938 | 2.161 | 2.981 | 1.894 | 3.503 | 1.751 |
|---|---|---|---|---|---|---|
| I/I₀ | 100 | 43.3 | 43.2 | 40.8 | 34 | 32.4 |
xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9000383; idealized occupancies, no preferred orientation.
Physical properties
| Density (calculated) | 2.947 g/cm³calculated from COD 9000383 |
|---|---|
| Hardness (Mohs) | 4.5-5single sourceFord, Dana's Textbook of Mineralogy, 3rd ed. (1922) |
| Specific gravity | 3.2 g/cm3single sourceFord, Dana's Textbook of Mineralogy, 3rd ed. (1922) |
| Color | redsingle sourceFord, Dana's Textbook of Mineralogy, 3rd ed. (1922) |
| Cleavage | imperfect, perfectsingle sourceFord, Dana's Textbook of Mineralogy, 3rd ed. (1922) |
Chemistry (calculated)
| Molecular weight | 414.02 g/molcalculated from the IMA formula |
|---|---|
| Composition (wt%) | Ca 9.68%, Al 19.55%, P 14.96%, O 54.1%, H 1.7% |
Classification
| Nickel-Strunz (10th) | 8.BL.10Wikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 8.BL.10Wikidata (CC0) |
| Dana (8th) | 42.7.3.1Wikidata (CC0) |