Tistarite

Tistarite is an exceedingly rare mineral with the formula Ti₂O₃, thus being the natural analogue of titanium(III) oxide.^[4][2] In terms of chemistry it is the titanium-analogue of hematite, corundum, eskolaite, and karelianite. Other minerals with the general formula A₂O₃ are arsenolite, avicennite, claudetite, bismite, bixbyite, kangite, sphaerobismoite, yttriaite-(Y) and valentinite. Tistarite and grossmanite – both found in the famous Allende meteorite (so is kangite) – are the only currently known minerals with trivalent titanium. Titanium in minerals is almost exclusively tetravalent.^[2][5][6] The only known terrestrial occurrence of tistarite was found during minerals exploration by Shefa Yamim Ltd. in the upper mantle beneath Mount Carmel, Israel.^[3][7]

Tistarite
General
Category	Oxide minerals
Formula	Ti2O3
IMA symbol	Tta[1]
Strunz classification	4.CB.05
Crystal system	Trigonal
Crystal class	Hexagonal scalenohedral (3m) H-M symbol: (3 2/m)
Space group	R3c
Identification
References	[2]

SEM BSE images showing kaitianite (Ktn) with tistarite (Tta), Ti,Al,Zr-oxide (TAZ), MgTi3+2Al4SiO12 phase (MTAS), spinel (Spl), sapphirine (Spr), and Ti-sulfide (Ti-S) in corundum Grain 1125C2. The upper rectangular area in (b) are enlarged in (c)^[3]