Melilite
Ca2M(XSiO7) M = Mg, Al, rarely Fe, B, Zn, Be, Si, etc. X = Si, Al, rarely Be or B.IMA symbol: Mllother:GROUP
Melilite is a mineral with the formula Ca2M(XSiO7) M = Mg, Al, rarely Fe, B, Zn, Be, Si, etc. X = Si, Al, rarely Be or B.. It has a Mohs hardness of 5, typically white, brown, green or red in color, with a resinous or vitreous luster, a specific gravity of 2.9-3.1. Its streak is white.
Photos
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Crystallography
| Space group | P -4 21 m |
|---|---|
| Cell (Å, °) | a = 7.754, b = 7.754, c = 5.101; α = 90, β = 90, γ = 90 |
| Cell volume | 306.695 ų, Z = 2 |
| Axial ratios | 1.0000:1:0.6579calculated from COD 9005464 |
| Source structure | COD 9005464 (European Journal of Mineralogy, 2001) — 1 of 19 structures |
Powder X-ray diffraction (calculated)
| d (Å) | 2.868 | 3.087 | 1.768 | 2.452 | 3.735 | 1.386 |
|---|---|---|---|---|---|---|
| I/I₀ | 100 | 27.2 | 25.3 | 20.4 | 17.2 | 13.2 |
xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9005464; idealized occupancies, no preferred orientation.
Physical properties
| Density (calculated) | 3.186 g/cm³calculated from COD 9005464 |
|---|---|
| Hardness (Mohs) | 5single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Specific gravity | 2.9-3.1 g/cm3single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Color | brown, green, red, white, yellowsingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Streak | whitesingle sourceWikidata (CC0) |
| Luster | resinous, vitreoussingle sourceDana, System of Mineralogy, 6th ed. (1892) |