:A very interesting piece under the microscope. Vesicles in this olivine nephelinite contain microcrystals of orange-brown, prismatic to platy oxykinoshitalite associated with nepheline, calcite, and an apatite group mineral. An unassuming specimen in hand sample, but fairly remarkable under modest magnification. Oxykinoshitalite is a rare and complex barium potassium magnesium titanium iron layer silicate and a member of the Mica Group. Ex. Paulo Matioli collection. 3.0 x 2.0 x 1.0 cm. From: Fernando de Noronha island, Fernando de Noronha archipelago, Pernambuco, Brazil. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Ulvöspinel
An iron-titanium spinel — the titanium end-member paired with magnetite in igneous rocks.
Intro adapted from Wikipedia (CC BY-SA).
Ulvöspinel is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Fe²⁺₂TiO₄.
It crystallizes in the cubic crystal system (space group Fd3m). It is a member of the Spinel structural group.
Key properties: Mohs hardness 5.75; specific gravity 4.78.
IMA symbol Uspl, grandfathered status — known before the IMA’s founding, named in 1946.
A common component of titaniferous magnetite iron ores; in kimberlites; in strongly reduced iron-bearing basalts, terrestrial and lunar.
It is found associated with Iron, magnetite, troilite, cohenite, graphite, ilmenite, pyrrhotite, chalcopyrite, olivine, pyroxene, biotite, plagioclase, apatite.
The name refers to the occurrence on the Ulvö Islands, Sweden, and as a member of the spinel group.