Orebody 31 (Chromite deposit 31), Luobusha Mine ("Luobusa" Mine), Luobusha ophiolite ("Luobusa ophiolite"), Qusum Co. (Qusong Co.), Shannan Prefecture (Lhokha Prefecture; Lhoka Prefecture), Tibet, Chinai

Regional Level Types
Orebody 31 (Chromite deposit 31)	Mine
Luobusha Mine ("Luobusa" Mine)	Mine
Luobusha ophiolite ("Luobusa ophiolite")	Outcrop
Qusum Co. (Qusong Co.)	County
Shannan Prefecture (Lhokha Prefecture; Lhoka Prefecture)	Prefecture
Tibet	Autonomous Region
China	Country

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Podiform chromite bodies hosted in a harzburgite formation of the Luobusha ophiolite, extending along the Yarlong Zangbo (Brahmaputra) River for about 42 km from E to W with a width of 1-4 km. The main rock type is harzburgite, with lesser amounts of dunite, mafic rocks, pillow lavas and a mix of different ophiolites. The chromite bodies are hosted in the mantle-derived harzburgite rocks, and represent a resource of ca. 5 Mt of ore (Shi et al., 2012):

An age of 126 Ma for the ophiolites is assumed, based upon comparison with other ophiolites in the same belt (Xia, 2011).

The holotype specimen of both maurogemmiite and paulrobinsonite is a fragment about 0.45 × 0.8 mm across, catalogue number M11843. The fragment used in this study was handpicked from a heavy mineral separate processed from 1500 kg of chromitite collected in 1996 from orebody #31 of the Luobusa ophiolite. Maurogemmiite forms irregular grains up to 30 μm across enclosed in paulrobinsonite. In some cases, maurogemmiite grains are cored by a Ti-rich phase and rimmed by paulrobinsonite, whereas in others, maurogemmite forms rings and irregular grains within paulrobinsonite. The inverse was also found; a lamella of paulrobinsonite ~1 μm thick in maurogemmiite. No contacts were observed between maurogemmiite and the symplectitic intergrowth of wangxibinite and “osbornite”; maurogemmiite was thus invariably isolated from the symplectite by paulrobinsonite. The paulrobinsonite rims are generally less than 40 μm thick. The vermicular symplectite composed of wangxibinite and “osbornite” in roughly equal proportions occupies irregular areas tens of µm across that are interstitial to paulrobinsonite grains. Individual vermicules generally range from 0.3 to 1 µm in width and from 1 to several µm in length. Overall, textural relationships suggest that titanium crystallised first and subsequently was overgrown by maurogemmiite, which was subsequently overgrown and partially replaced by paulrobinsonite, resulting in some interleaving of maurogemmiite and paulrobinsonite. The vermicular symplectite of “osbornite” and wangxibinite, together with minor titanium, crystallised last, filling the interstices between grains of paulrobinsonite. One fragment recovered from the chromitite, sample M11843, is noteworthy for an especially diverse assemblage. Although only 450 μm × 800 μm in size, this fragment contains 11 minerals including the two new species described here, maurogemmiite Ti10Fe3O3 (IMA 2022-098a), and paulrobinsonite, Ti8Fe4O2 (IMA 2022-099a). The fragment was extracted from chromitite orebody #31 in the Luobusa ophiolite near Luobusa Village, Tibet, China. The assemblage in the alloy core of sample M11843 includes the type titanium (α-Ti) (Fang et al. 2013), “osbornite” (Ti nitride), wangixibinite (TiFe) and the two new minerals reported here.

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.

Mineral List

14 valid minerals. 6 (TL) - type locality of valid minerals.

Rock Types Recorded