Ulvöspinel or ulvite is an iron titanium oxide mineral with formula: Fe₂ Ti O₄ or TiFe²⁺₂O₄. It forms brown to black metallic isometric crystals with a

Mohs hardness The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by t ...

of 5.5 to 6. It belongs to the

spinel group The spinels are any of a class of minerals of general formulation which crystallise in the cubic (isometric) crystal system, with the X anions (typically chalcogens, like oxygen and sulfur) arranged in a cubic close-packed lattice and the cation ...

of minerals, as does

magnetite Magnetite is a mineral and one of the main iron ores, with the chemical formula Fe2+Fe3+2O4. It is one of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself. With th ...

, Fe₃O₄. Ulvöspinel forms as

solid solution A solid solution, a term popularly used for metals, is a homogenous mixture of two different kinds of atoms in solid state and have a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The wor ...

s with magnetite at high temperatures and reducing conditions, and grains crystallized from some

basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...

gabbro Gabbro () is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is ch ...

magmas are rich in the ulvöspinel component. The ulvöspinel component tends to oxidize to magnetite plus

ilmenite Ilmenite is a titanium-iron oxide mineral with the idealized formula . It is a weakly magnetic black or steel-gray solid. Ilmenite is the most important ore of titanium and the main source of titanium dioxide, which is used in paints, printing ...

during subsolidus cooling of the host rocks, and the ilmenite so produced may form apparent

exsolution A solid solution, a term popularly used for metals, is a homogenous mixture of two different kinds of atoms in solid state and have a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The wor ...

(trellis type) laminae in

. The texture was once interpreted as indicating solid solution between ilmenite and magnetite, until the oxidation reaction and resultant textures were reproduced in laboratory experiments first described by Buddington and Lindsley (1964, Journal of Petrology 5, p. 310-357). The results are important to

plate tectonics Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large ...

because magnetite is an important recorder of rock magnetism. Ulvöspinel was first described by Fredrik Mogensen (1904-1978) from a

dolerite Diabase (), also called dolerite () or microgabbro, is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grain ...

layered intrusion in the Ulvö Islands,

Ångermanland Ångermanland ( or ) is a historical province (''landskap'') in the northern part of Sweden. It is bordered (clockwise from the north) by Swedish Lapland, Västerbotten, the Gulf of Bothnia, Medelpad and Jämtland. The name is derived from ...

, Sweden in 1943. The locality is an iron, titanium and vanadium mining area that has been active since the 17th century. It is common in titaniferous magnetite iron ore deposits. It also occurs in

kimberlite Kimberlite is an igneous rock and a rare variant of peridotite. It is most commonly known to be the main host matrix for diamonds. It is named after the town of Kimberley in South Africa, where the discovery of an diamond called the Star of S ...

s, in some reduced iron-bearing

s and is common in

lunar Lunar most commonly means "of or relating to the Moon". Lunar may also refer to: Arts and entertainment * ''Lunar'' (series), a series of video games * "Lunar" (song), by David Guetta * "Lunar", a song by Priestess from the 2009 album ''Prior t ...

basalts.

References

Spinel group Cubic minerals Minerals in space group 227 {{oxide-mineral-stub