Carbide‐Nitride Assemblages of the Earth's Crustal Telluric Iron: A Possible Key to Unraveling the Formation Pathways of Metal Rich Asteroids

Abstract Iron is one of the most common elements on Earth and is present in the modern crust mainly in the form of (hydro)oxides and silicates, whereas terrestrial (telluric) native Fe is extremely rare. It is generally assumed that telluric Fe differs greatly in its chemical composition and mineralogy from the metal of iron meteorites, indicating different modes of formation. We uncover haxonite (NiFe 22 C 6 ) and uakitite (VN) within telluric iron assemblages in terrestrial crustal rocks (volcanic rocks of the Norilsk ore region, Russia and metamorphic rocks of the Hatrurim Basin, Israel, respectively). Both minerals were previously discovered in iron meteorites and were thought to be absent in Earth's crustal rocks. Consequently, we analyzed available data on terrestrial rocks containing native iron and iron meteorites and compared their oxygen‐free mineral assemblages. The resemblance in mineralogy suggests that at least some metal‐rich asteroids may have formed in a manner similar to telluric iron. We suggest that heating at low pressures ( T ≈ 1000°C, P < 10 MPa) of the primary Fe‐bearing silicates in the presence of organic matter led to the formation of an iron melt at low oxygen fugacity (up to 5 units below Fe‐FeO buffer). Significant differences in the geochemistry of terrestrial and extraterrestrial iron are associated with different degrees of evolution of the primary minerals involved in their formation.