Griffinite (IMA 2021-110), ideally Al
2TiO
5, is a new mineral from inclusions in corundum xenocrysts from the Mount Carmel area, Israel. It occurs as subhedral crystals, ~1–4 μm in size, together with Zr-rich rutile within a corundum grain. In this
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Griffinite (IMA 2021-110), ideally Al
2TiO
5, is a new mineral from inclusions in corundum xenocrysts from the Mount Carmel area, Israel. It occurs as subhedral crystals, ~1–4 μm in size, together with Zr-rich rutile within a corundum grain. In this study, a mean of eight electron probe microanalyses gave TiO
2 44.41 (24), Al
2O
3 55.13 (18), FeO 0.47 (5), and MgO 0.37 (2), totaling 100.38 wt%, which corresponded, on the basis of a total of five oxygen atoms, to (Al
1.97Mg
0.02Fe
0.01)Ti
1.01O
5. Electron back-scatter diffraction studies revealed that griffinite is orthorhombic and in the space group
Cmcm, with
a = 3.58 (2) Å,
b = 9.44 (1) Å,
c = 9.65 (1) Å, and
V = 326 (2) Å3 with
Z = 4. The six strongest calculated powder diffraction lines [
d in Å (
I/
I0) (
hkl)] are 3.347 (100) (110); 2.658 (90) (023); 4.720 (77) (020); 1.903 (57) (043); 1.790 (55) (200); and 1.688 (44) (134). In the crystal structure, Al
3+ and Ti
4+ are disordered into two distinct distorted octahedra, which form edge-sharing double chains. Griffinite is a high-temperature oxide mineral, formed in melt pockets in corundum-aggregate xenoliths derived from the upper mantle beneath Mount Carmel, Israel. The new mineral is named after William L. Griffin, a geologist at Macquarie University, Australia.
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