Lawsonite
CaAl2(Si2O7)(OH)2·H2OIMA symbol: Lwsgrandfathered
Lawsonite is a silicate mineral with the formula CaAl2(Si2O7)(OH)2·H2O, crystallizing in the orthorhombic system. It has a Mohs hardness of 5.5, typically brown or gray in color, with a greasy or vitreous luster, a specific gravity of 3.09. Its streak is white.
Photos
Crystallography
| Crystal system | orthorhombic crystal systemWikidata (CC0) |
|---|---|
| Space group | C m c m |
| Cell (Å, °) | a = 5.8417, b = 8.7904, c = 13.1345; α = 90, β = 90, γ = 90 |
| Cell volume | 674.468 ų, Z = 4 |
| Axial ratios | 0.6646:1:1.4942calculated from COD 9014408 |
| Source structure | COD 9014408 (American Mineralogist, 2010) — 1 of 33 structures |
Physical properties
| Density (calculated) | 3.068 g/cm³calculated from COD 9014408 |
|---|---|
| Hardness (Mohs) | 7.5single sourceWikidata (CC0) 5.5single sourceFord, Dana's Textbook of Mineralogy, 3rd ed. (1922) |
| Specific gravity | 3.09 g/cm3corroboratedFord, Dana's Textbook of Mineralogy, 3rd ed. (1922) |
| Color | brown, graysingle sourceFord, Dana's Textbook of Mineralogy, 3rd ed. (1922) |
| Streak | whitesingle sourceWikidata (CC0) |
| Luster | greasy, vitreousFord, Dana's Textbook of Mineralogy, 3rd ed. (1922) |
Chemistry (calculated)
| Molecular weight | 314.24 g/molcalculated from the IMA formula |
|---|---|
| Composition (wt%) | Ca 12.75%, Al 17.17%, Si 17.88%, O 50.91%, H 1.28% |
Classification
| Nickel-Strunz (10th) | 9.BE.05Wikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 9.BE.05Wikidata (CC0) |
| Dana (8th) | 56.2.3.1Wikidata (CC0) |