Margarite
CaAl2Si2Al2O10(OH)2IMA symbol: Mrgapproved
Margarite is a silicate mineral with the formula CaAl2Si2Al2O10(OH)2, crystallizing in the monoclinic system. It has a Mohs hardness of 3.5-4.5, typically white, gray, pink or red in color, with a pearly or vitreous luster, a specific gravity of 2.99-3.08. Cleavage is perfect.
Photos
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Crystallography
| Crystal system | monoclinic crystal systemWikidata (CC0) |
|---|---|
| Space group | C 1 c 1 |
| Cell (Å, °) | a = 5.108, b = 8.844, c = 19.156; α = 90, β = 95.48, γ = 90 |
| Cell volume | 861.42 ų, Z = 4 |
| Axial ratios | 0.5776:1:2.1660calculated from COD 9016300 |
| Source structure | COD 9016300 (Zeitschrift fur Kristallographie, 1983) — 1 of 2 structures |
Powder X-ray diffraction (calculated)
| d (Å) | 2.512 | 3.178 | 1.474 | 2.517 | 2.888 | 4.375 |
|---|---|---|---|---|---|---|
| I/I₀ | 100 | 76.4 | 69.2 | 57.9 | 55.4 | 54.6 |
xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9016300; idealized occupancies, no preferred orientation.
Physical properties
| Density (calculated) | 3.048 g/cm³calculated from COD 9016300 |
|---|---|
| Hardness (Mohs) | 3.5-4.5single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Specific gravity | 2.99-3.08 g/cm3corroboratedDana, System of Mineralogy, 6th ed. (1892) |
| Color | gray, pink, red, white, yellowsingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Luster | pearly, vitreoussingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Cleavage | perfectDana, System of Mineralogy, 6th ed. (1892) |
Chemistry (calculated)
| Molecular weight | 398.18 g/molcalculated from the IMA formula |
|---|---|
| Composition (wt%) | Ca 10.07%, Al 27.1%, Si 14.11%, O 48.22%, H 0.51% |
Classification
| Nickel-Strunz (10th) | 9.EC.30Wikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 9.EC.30Wikidata (CC0) |