Willemite
Zn2SiO4IMA symbol: Wlmgrandfathered
Willemite is a silicate mineral with the formula Zn2SiO4, crystallizing in the trigonal system. It has a Mohs hardness of 5.5, typically white, gray, green or red in color, with a resinous luster, a specific gravity of 3.89-4.18. Its streak is red.
Photos
.jpg){kind=link}
.jpg){kind=link}
_(14755145076).jpg){kind=link}
Crystallography
| Crystal system | trigonal crystal systemWikidata (CC0) |
|---|---|
| Space group | R -3 :H |
| Cell (Å, °) | a = 13.948, b = 13.948, c = 9.315; α = 90, β = 90, γ = 120 |
| Cell volume | 1569.41 ų, Z = 18 |
| Axial ratios | 1.0000:1:0.6678calculated from COD 9007627 |
| Source structure | COD 9007627 (Acta Crystallographica, Section B, 1978) — 1 of 5 structures |
Powder X-ray diffraction (calculated)
| d (Å) | 2.636 | 2.837 | 3.487 | 2.319 | 1.861 | 1.422 |
|---|---|---|---|---|---|---|
| I/I₀ | 100 | 87.6 | 72.5 | 54.4 | 45.2 | 42.9 |
xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9007627; idealized occupancies, no preferred orientation.
Physical properties
| Density (calculated) | 4.245 g/cm³calculated from COD 9007627 |
|---|---|
| Hardness (Mohs) | 5.5single sourceWikidata (CC0) 5.5single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Specific gravity | 3.89-4.18 g/cm3single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Color | gray, green, red, white, yellowsingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Streak | redsingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Luster | resinoussingle sourceDana, System of Mineralogy, 6th ed. (1892) |
Chemistry (calculated)
| Molecular weight | 222.9 g/molcalculated from the IMA formula |
|---|---|
| Composition (wt%) | Zn 58.69%, Si 12.6%, O 28.71% |
Classification
| Nickel-Strunz (10th) | 9.AA.05Wikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 9.AA.05Wikidata (CC0) |
| Dana (8th) | 51.1.1.2Wikidata (CC0) |