4.4" Roselite and Calcite Crystal Association - Morocco
This is a beautiful association of very richly colored roselite crystal aggregates and calcite that was collected from the Bou Azer District of Morocco.
Roselite is a monoclinic mineral of the hydrated phosphates group, and has a chemical formula of Ca2Co(AsO4)2 · 2H2O. It gained its name not from the rose color that is generally exhibited by the mineral, but was in fact named in honor of a German mineralogist by the name of Gustav Rose. However, the name is quite fitting, for roselite typically displays a vitreous rose-red to pink color. Darker colored crystals have been known to frequently display marked color zoning due to variations in molecular composition.
Calcite, CaCO3, is a carbonate mineral and the most stable polymorph of calcium carbonate. The other polymorphs are the minerals aragonite and vaterite. Calcite crystals are trigonal-rhombohedral, though actual calcite rhombohedra are rare as natural crystals. However, they show a remarkable variety of habits including acute to obtuse rhombohedra, tabular forms, and prisms. Calcite exhibits several twinning types adding to the variety of observed forms. It may occur as fibrous, granular, lamellar, or compact. Cleavage is usually in three directions parallel to the rhombohedron form.