Hawthorneite
Hawthorneite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula BaMgTi₃Cr₄Fe²⁺₂Fe³⁺₂O₁₉.
It crystallizes in the hexagonal crystal system (space group P6_3/mmc). It is a member of the Magnetoplumbite structural group.
Key properties: Mohs hardness 5.8; specific gravity 5.02; optically uniaxial.
IMA symbol Hwt, IMA status: approved, named in 1988.
developed during upper-mantle (75–100 km, 900–1100 ° C, 20–30 kbar) metasomatism of chromian spinel in peridotite xenoliths in a kimberlite pipe.
It is found associated with Olivine, enstatite, phlogopite, potassian richterite, diopside, magnesian chromian spinel, lindsleyite, mathiasite, niobian chromian rutile.
The name refers to John Barry Hawthorne (1934–), formerly Chief Geologist (Diamonds), DeBeers Consolidated Mines, South Africa, in honor of his contributions to studies of the upper mantle.