Metallionia

Metallionia is a rare metallic mineral described in speculative mineralogy as an iron–nickel intermetallic alloy with trace chromium and vanadium. It is reported to form as elongated, subhedral crystals with a bright metallic luster, typically silver-gray in color, and a high density. The mineral’s hardness is estimated around 5.5–6 on the Mohs scale, and it often exhibits weak magnetism.

Chemistry and structure are described as primarily iron and nickel in a closely packed intermetallic lattice, with minor cobalt and trace chromium, vanadium, and manganese. Reported crystal habits range from prismatic to tabular; some collections assign a tetragonal system, though no single crystal structure is universally accepted. The name reflects its designation as a metal-bearing intermetallic phase in speculative discussions.

Occurrence and discovery are limited to a few ultramafic or sulfide-poor rock contexts from isolated metallic-rich intrusions. Because metallionia has not been officially validated by major mineral authorities, reports remain anecdotal and samples are exceedingly rare. The locality and exact formation conditions are therefore uncertain.

Status and terminology: The International Mineralogical Association has not recognized metallionia as a formal mineral species, and many references treat it as either a hypothetical or fictional mineral rather than a sanctioned name. The term is derived from metallum (Latin for metal) and ion, used in discussions about metallic intergrades in speculative contexts.

Applications and research: If confirmed, metallionia could offer insights into high-temperature intermetallics and inspire new alloy concepts. Given its speculative status, there are no commercial applications at present, and research remains preliminary.