Hemimorphite necklace with 6mm beads (also known as Chinese Larimar)

The mineral hemimorphite (also called calamine) is a hydrated zinc silicate with the chemical formula Zn4Si2O7(OH)2 H2O. It belongs to the sorosilicates. The mineral mainly occurs as an oxidation product in the top layer of zinc blend deposits. Well-known sites are the Belgian-German border, Silesia in Poland, and the states of Pennsylvania and Missouri in the United States. Hemimorphite is one of the most common sorosilicates. Its most notable feature is the polar or hemimorphic crystals from which it gets its name. The crystal structure gives a different end to each end of the crystal. A termination, the "bottom" is rather blunt dominated by a Pedion face, while the other side, the "top" is terminated by the tip of a pyramid. The crystal structure contains tetrahedrons of ZnO 3 OH locked with Si 2 O 7 groups and water molecules. The zinc is at the center of the tetrahedron, while the three oxygen atoms, along with an OH group, are at the four points of the tetrahedron. The tetrahedra are all aligned in the same direction with a plane parallel to the pedion termination and the "top" of the tetrahedra toward the pyramidal termination.