| Roselite | |
|---|---|
 | |
| General | |
| Category | Arsenate minerals |
| Formula | Ca2(Co2+, Mg)[AsO4]2·H2O+ |
| IMA symbol | Rsl[1] |
| Strunz classification | 8.CG.10 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (sameH-M symbol) |
| Space group | P21/c |
| Unit cell | a = 5.801 Å, b = 12.898 Å c = 5.617 Å; β = 107.42°; Z = 2 |
| Identification | |
| Color | Dark rose red, pink |
| Crystal habit | Elongated crystals and spherical aggregates anddruses |
| Twinning | Common as composition plane, contact twins and fourlings |
| Cleavage | {010} Perfect |
| Mohs scale hardness | 3.5 |
| Luster | Vitreous |
| Streak | Light red |
| Specific gravity | 3.69 |
| Optical properties | Biaxial (−) |
| Refractive index | nα = 1.725 nβ = 1.728 nγ = 1.735 |
| Pleochroism | (Dark rose) X: Dark rose, Y: Pale rose, Z: Paler rose (Light rose) X: Pale rose, Y: Paler rose, Z: Palest rose |
| 2V angle | Calculated: 68° |
| References | [2][3][4] |
Roselite is a rarearsenate mineral with chemical formula:Ca2(Co,Mg)[AsO4]2·H2O. It was first described in 1825 for an occurrence in the Rappold mines ofSchneeberg,Saxony,Germany and named byArmand Lévy after German mineralogistGustav Rose.[2] It occurs incobalt-bearinghydrothermal environments and was associated withveins ofquartz andchalcedony in thetype locality.[2][4] It has also been reported fromItaly,Morocco,Chile,British Columbia and several locations in Germany.[2]
Thepleochroism of roselite depends on chemical composition with darker-rose-colored varieties higher in cobalt content and lighter-rose-colored varieties higher incalcium andmagnesium content (Palache et al., 1960). This gives rise to two different pleochroism schemes, one for dark rose and one for light rose. Dark rose varieties have X: dark rose, Y: pale rose, Z: paler rose. Light rose varieties have X: pale rose, Y: paler rose, Z: palest rose.
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