4 Formed and Polished GREEN BANDED ONYX Mineral Spheres. They all measure approximately 2" in Diameter and the Total Weight is 1 lb 8 oz. Green Banded Onyx is a sedimentary stone composed of banded calcite and aragonite, formed in caves, fissures, and hot springs. This is genuine, natural onyx with varied color and banding patterns. Onyx is used for home decor and for its perceived metaphysical properties as a grounding stone. ROCKS FOSSILS MINERALS