zircon

Called also jargon of Ceylon, a mineral originally found in Ceylon, in the sands of rivers, along with spinel, sapphire, tourmalin, and iron sand. Zircon, hyacinth, and zirconite, are regarded as varieties of the same species. They are essentially composed of the earth zirconia, with silex, and a minute portion of iron. The primitive form of the crystals is an octahedron, composed of two four sided prisms. The common form is a rectangular four sided prism.