4.8" Blue Bladed Barite Crystal Clusters with Calcite - Morocco
This is a spectacular, specimen of bladed blue barite that formed in association with calcite. The calcite encrusts most of the matrix, with a gorgeous, 1" wide cluster of blue bladed barite (among other smaller clusters) that formed over the calcite. The entire specimen measures 4.8 x 3.2" and it was collected from the Nador Province of Morocco.
Barite, commonly spelled baryte, is well-known for its great range of colors and varied crystal forms and habits. It is a heavy mineral consisting of barium sulfate, and typically has the chemical formula of BaSO4. The barite group consists of baryte, celestine, anglesite and anhydrite. It's generally white to colorless and is the main source of barium.
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.