Redutorite

Redutorite is a rare oxide mineral described as a member of the spinel group. Its idealized formula is (Fe2+,Mg)2+(Fe3+,Al)O4, reflecting a mixed-valence composition with iron and aluminum substitutions. The name is derived from redox-related formation conditions and the mineral’s characteristic red to reddish-brown color, which arises from ferric iron.

In terms of crystallography, redutorite crystallizes in the isometric system and commonly forms small, well-formed octahedral or subhedral crystals, though it is more often seen as fine-grained masses. It has a vitreous to metallic luster, a hardness of 6.0–6.5 on the Mohs scale, and a specific gravity around 4.1–4.3. The color range is typically deep red to brownish red, and crystals can be transparent to translucent in fine grains and opaque in coarser aggregates.

Redutorite occurs in high-temperature hydrothermal veins hosted by basaltic and ultramafic rocks. It is usually found associated with magnetite, hematite, ilmenite, quartz, and other oxides. Its occurrence can provide information about redox conditions during ore formation and the evolution of hydrothermal systems. Although not a major ore mineral, redutorite is of interest to researchers studying oxide mineralogy and geochemical processes in reducing environments.

Etymology and history indicate that redutorite was named to emphasize the reductive conditions of its formation and its distinctive coloration. It remains a subject of interest mainly to mineralogists and collectors due to its rarity and striking color.