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Formula: (Al0.67☐0.33)Al2O4
Oxide, spinel subgroup,
oxyspinel group,
spinel supergroup
Crystal System: Tetragonal
Specific gravity: 3.663 calculated
Colour: Pale yellowish, pale beige or white
Environments
Deltalumite is a relatively new mineral, approved in 2016.
Localities
At Orebody CR-11, Kangjinla Cr deposit, Luobusha ophiolite, Qusum Co. (Qusong Co.), Shannan Prefecture
(Lhokha Prefecture; Lhoka Prefecture), Tibet, China, jingsuiite,
osbornite-khambaraevite,
deltalumite and wenjiite constitute four inclusions up to 50 μm
across in corundum recovered from the orebody. In one inclusion,
jingsuiite,
osbornite-khambaraevite,
deltalumite and wenjiite form a lamellar intergrowth 100 μm long
composed of tablets of the four phases up to 50 μm long × 4 μm in thickness
(AM 107.1.43–53).
At the type locality, the 2012-2013 Fissure Tolbachik Eruption site, Plosky Tolbachik Volcano, Tolbachik Volcanic
field, Milkovsky District, Kamchatka Krai, Russia, deltalumite occurs as roundish aggregations up to 0.2 mm
across which consist of blocky, coarse prismatic individuals up to 0.03 mm in size, found in pores of
basalt lava and basalt
scoria altered by fumarolic gas
(Mindat).
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