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Roselite druse in a vug from Morocco (size:12.8 x 8.5 x 5.9 cm)
Category Arsenate minerals
(repeating unit)
Ca2(Co2+, Mg)[AsO4]2·H2O
Strunz classification 8.CG.10
Crystal system Monoclinic
Crystal class Prismatic (2/m)
H-M symbol: (2/m)
Space group Monoclinic
Space group: P21/c
Unit cell a = 5.801 Å, b = 12.898 Å
c = 5.617 Å; β = 107.42°; Z = 2
Color Dark rose red, pink
Crystal habit Elongated crystals and spherical aggregates and druses
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 Visible
2V angle Calculated: 68°
References [1][2][3]

Roselite is a rare arsenate mineral with chemical formula: Ca2(Co,Mg)[AsO4]2·H2O. It was first described in 1825 for an occurrence in the Rappold mines of Schneeberg, Saxony, Germany and named by Armand Lévy after German mineralogist Gustav Rose.[1] It occurs in cobalt bearing hydrothermal environments and was associated with veins of quartz and chalcedony in the type locality.[1][3] It has also been reported from Italy, Morocco, Chile, British Columbia and several locations in Germany.[1]