What is Ulvöspinel?
Ulvöspinel is a titanium-rich iron oxide in the magnetite-ulvöspinel series, important in igneous petrology and recognised in dark, dense oxide grains.
Mineralogy and structure
Reference formula: Fe2TiO4. Ulvöspinel has a cubic spinel structure and forms a solid-solution series with magnetite. COD 9004155 is a ferrian ulvöspinel representative, so the generated model is labelled accordingly rather than presented as an analysis of every specimen. Ulvöspinel is classified with oxides and has cubic crystal symmetry. Typical hardness is 5.5–6 on the Mohs scale and specific gravity is approximately 4.7–4.8.
Colour, lustre and habit
Typical colours include black, brown-black, steel-grey. The usual octahedral, granular, massive habit and metallic, sub-metallic lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Ulvöspinel forms in or is associated with mafic and ultramafic igneous rocks, titaniferous magnetite deposits and metamorphic oxide assemblages. Important documented localities include Sweden, Norway, Canada, South Africa, Russia, Australia and the United States.
Titanium and iron in a dark spinel framework
Ulvöspinel is a specialist collector and teaching mineral: its black appearance records oxide crystallisation in mafic magma, while its relationship to magnetite explains why composition matters.
Collecting and care
Protect from impact and abrasion; keep magnetic associations and host-rock information with the specimen. Avoid claiming a precise end-member composition without analysis.
