Halloysite
Al2Si2O5(OH)4IMA symbol: Hlyrenamed
Halloysite is a silicate mineral with the formula Al2Si2O5(OH)4, crystallizing in the monoclinic system. It has a Mohs hardness of 2.25, typically white, blue, gray or green in color, with a dull or pearly luster, a specific gravity of 2.469.
Photos
Crystallography
| Crystal system | monoclinic crystal systemWikidata (CC0) |
|---|---|
| Space group | C 1 m 1 |
| Cell (Å, °) | a = 5.2, b = 8.92, c = 10.25; α = 90, β = 100, γ = 90 |
| Cell volume | 468.2 ų, Z = 2 |
| Axial ratios | 0.5830:1:1.1491calculated from COD 1011246 |
| Source structure | COD 1011246 (Zeitschrift fuer Kristallographie, Kristallgeometrie, Kristallphysik, Kristallchemie (-144,1977), 1935) — 1 of 2 structures |
Powder X-ray diffraction (calculated)
| d (Å) | 5.047 | 4.441 | 10.094 | 4.46 | 2.9 | 2.214 |
|---|---|---|---|---|---|---|
| I/I₀ | 100 | 56.7 | 41.4 | 36.4 | 34.6 | 23.8 |
xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 1011246; idealized occupancies, no preferred orientation.
Physical properties
| Density (calculated) | 2.03 g/cm³calculated from COD 1011246 |
|---|---|
| Hardness (Mohs) | 2.25single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Specific gravity | 2.469 g/cm3single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Color | blue, gray, green, red, white, yellowDana, System of Mineralogy, 6th ed. (1892) |
| Luster | dull, pearly, waxyDana, System of Mineralogy, 6th ed. (1892) |
Chemistry (calculated)
| Molecular weight | 258.16 g/molcalculated from the IMA formula |
|---|---|
| Composition (wt%) | Al 20.9%, Si 21.76%, O 55.78%, H 1.56% |
Classification
| Nickel-Strunz (10th) | 9.ED.10Wikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 9.ED.10Wikidata (CC0) |