Gyarub Zangbo Pallasite Meteorite Slice, Ungrouped Pallasite, 84.69g, Tibet

An 84.69g etched slice of Gyarub Zangbo, an ungrouped pallasite from Tibet

This is an 84.69 gram polished and etched slice of Gyarub Zangbo, a pallasite recovered on the Qinghai-Tibet Plateau. It is a full-face section, and backlit, olivine crystals across the entire slice transmit gold and amber. Gyarub Zangbo is not a main group pallasite. The Meteoritical Society revised its classification to Pallasite, ungrouped in Meteoritical Bulletin 114, published in 2026, and as of September 2026 it is 1 of 17 approved meteorites carrying that classification. For background on the type, see our guide on what a pallasite is. The photographs show the exact specimen offered.

Structure and features of this slice

Olivine is distributed across the whole face, with dense crystal fields toward the margins and more open, metal-rich areas through the middle of the face. Grains range from small isolated crystals to larger clustered groups. The two faces are photographed separately, and the olivine pattern differs between them, as expected for a slice cut through a coarse aggregate.

The transmitted-light photographs show how many of the crystals remain translucent. Under strong backlight they read gold, amber and orange, while more weathered grains stay dark brown.

The metal between the crystals has been etched to reveal a fine crosshatched pattern, the intergrowth of kamacite and taenite that the Bulletin records as the metal phases in this meteorite. The macro photographs show the pattern clearly. The Bulletin describes Gyarub Zangbo as a coarse grained aggregate with a mean grain size of about 5 mm and a simple mineralogy of olivine and metal.

Published geochemistry from the Bulletin: olivine Fa21.6±0.4 with Fe/Mn 66.9±3.9 (n=41). The MB 114 reclassification added orthopyroxene Fs19.1±2.3Wo2.0±0.8 (N=21), augite Fs8.2±0.4Wo43.0±1.6 (N=6) and two populations of chromite (Mg# 21.5±0.6 and 8.0±3.2), together with troilite, schreibersite and the phosphates stanfieldite and farringtonite. Oxygen isotopes reported in MB 114 give Δ17O of −2.262 and −2.2385‰ (H. Bao, Nanjing University) and −2.230‰ (D. Ibarra and R. Havel, Brown University). The Bulletin records a shock stage of low and a weathering grade of low.

Both faces carry a thin protective epoxy. The coating stabilizes the olivine and slows oxidation, and is standard practice for pallasite preservation.

Discovery and provenance

Gyarub Zangbo was found in October 2020 by G. Tulga during exploration of the uninhabited Qiangtang region of the Qinghai-Tibet Plateau, northeast of the Gyarub Zangbo river in Xizang, China, at 33.126°N, 87.079°E. The recovery consisted of many disaggregated fragments of olivine and metal, with a larger metal-rich specimen found nearby. All of the material was purchased by Ziyao Wang in October and November 2020, and the Bulletin records the main mass as being with him.

The type specimen, 120 g including two polished end cuts, is held at the Burke Museum of Natural History and Culture at the University of Washington. Classification was carried out by A. Irving at the University of Washington and P. Carpenter at Washington University in St. Louis, and the name was approved on 13 March 2021. This specimen was acquired by Treasure Coast Meteorite Co.

The Bulletin indexes a mass of 17.61 kg in 102 pieces from the original MB 110 entry. The MB 114 reclassification writeup states that the updated total mass is now more than 200 kg, so the indexed figure covers only the material in the first announcement. Browse related specimens in our Stony-Iron Meteorites collection.

Scientific context

Most pallasites belong to the main group, which shares a parent body tied to the IIIAB irons. Gyarub Zangbo fits neither the main group nor the Eagle Station group, and the Bulletin sets out why. Its olivine is close in composition to Eagle Station olivine but has lower Fe/Mn ratios, and is clearly distinct from main group olivine. It contains pyroxene, which is absent from both groups. Its oxygen isotopes fall on an array between main group and Eagle Station values without overlapping any other ungrouped pallasite. Its metal shows affinity with the IIF irons rather than the IIIAB irons, and carries more nickel than the metal of the IVB irons, the Eagle Station pallasites and the main group. Ga and Ge contents also separate it from both groups.

What the 2023 studies report

Two abstracts presented at the 54th Lunar and Planetary Science Conference in 2023 examined Gyarub Zangbo in detail, and they remain the published research on this meteorite beyond the Bulletin itself. Their figures come from the authors' own samples and methods, not from the Bulletin, and are given here as the studies state them. The two groups analysed different material in different laboratories, so their numbers do not always agree.

Jiang et al. (2023): an anomalous carbonaceous pallasite

Y. Jiang, X. R. Zhang, W. Z. He, S. Y. Liao, C. Herd, Y. B. Peng and W. B. Hsu, of Purple Mountain Observatory, the University of Alberta and Nanjing University, published Gyarub Zangbo: An anomalous carbonaceous pallasite (LPI Contrib. No. 2806, abstract #1183).

Petrography. The authors describe the interior as roughly 60 percent olivine and 36 percent metal by volume. The metal is mainly taenite decorated by wavy kamacite bands, and the minor phases are troilite, schreibersite, chromite, phosphate and pyroxene. Orthopyroxene grows on the edges of olivine grains or occurs scattered, and chromite occasionally sits on the contacts between olivine and metal.

Mineral chemistry. Olivine is highly homogeneous at Fa21.6±0.4 (Fe/Mn 66.9±3.9, n=41), which the authors note is more iron-rich than the olivine of any other pallasite previously reported. Main group pallasite olivine, by comparison, runs Fa11 to 13. Orthopyroxene is magnesium-rich at En80.3±0.3Fs19.14±0.2Wo0.55±0.3 (Fe/Mn 43.9±4.4, n=13). Two kinds of chromite are present, with Mg# of 21.5±0.6 and 8.0±3.2 and Cr# of 87.8±0.6 and 100.

Metal chemistry. Metal was analysed by ICP-MS at the University of Alberta:

Isotopes. Olivine, hand-picked to remove weathered material, was analysed by laser fluorination at Nanjing University, giving δ17O = −1.294±0.006‰, δ18O = 1.824±0.005‰ and Δ17O = −2.262±0.004‰. Chromium isotopes gave ε54Cr of 3.05±0.32 and ε53Cr of 1.57±0.10, which the authors note are not corrected for cosmogenic effects. Gyarub Zangbo occupies a unique position on their combined oxygen and chromium isotope plot.

Interpretation. Compared with main group pallasites, Gyarub Zangbo olivine is richer in iron with lower Δ17O, and its metal carries more nickel and iridium. The authors see chemical affinities with carbonaceous pallasites, namely the Eagle Station grouplet (olivine Fa19 to 20) and the ungrouped carbonaceous pallasite Milton (Fa17.2). They describe the metal as IIF iron-like, with gallium similar to Milton but higher than the Eagle Station pallasites, and a tungsten depletion relative to osmium and iridium that is less pronounced than in either. They single out its low germanium content as its most notable feature, and conclude that mineral chemistry, olivine oxygen and chromium isotopes and metal chemistry together make Gyarub Zangbo an anomalous carbonaceous pallasite, sampled from an asteroid not previously represented in pallasite collections.

Boesenberg et al. (2023): the tenth pyroxene pallasite

J. S. Boesenberg, M. Humayun, A. J. Irving and D. E. Ibarra, of Brown University, the National High Magnetic Field Laboratory at Florida State University and the University of Washington, published New pyroxene pallasites: Bordji Badji Mokhtar 001 and Gyarub Zangbo, and a plethora of pallasite parent bodies (LPI Contrib. No. 2806, abstract #2392).

Discovery of pyroxene. Gyarub Zangbo was first announced simply as a pallasite, and its olivine composition looked typical of the Eagle Station group, so the authors studied it mainly to analyse its metal. Electron microprobe work at Brown University then found orthopyroxene, making Gyarub Zangbo the tenth known pyroxene pallasite.

Silicates and chromite. The authors report that Gyarub Zangbo contains the most iron-rich olivine and chromite found in any pallasite. Olivine is Fa20.9 to 22.4 (Fe/Mn 53 to 68), in grains up to 5 mm that range from rounded to angular. Orthopyroxene, Wo0.2En79.5 to Wo0.5En80.9 (Fe/Mn 35 to 40, 0.12 to 0.17 wt% Cr2O3), occurs in coarse orthopyroxene, troilite and olivine intergrowths and as single rounded grains on the outer edges of larger olivines, mostly 50 to 200 microns across. Chromite is scarce and small, 20 to 40 microns, and low in aluminium (0.33 to 2.43 wt% Al2O3).

Metal. Swathing kamacite and interior taenite are both present, with troilite and schreibersite. Metal analysed at Florida State University plots, on the gallium versus gold diagram, where main group pallasites merge with the IIIAB irons, and on the iridium versus gold diagram beyond the iridium-rich end of the main group, which the authors read as early crystallizing metal. Their measured gallium (15 ppm) is higher and germanium (24 ppm) lower than in Eagle Station pallasites (3 to 9 ppm gallium, 75 to 130 ppm germanium). Nickel is higher than in the IVB irons or Eagle Station pallasites, and together with gallium and germanium places the meteorite in ungrouped status. Oxygen isotopes were still pending when the abstract was written; later measurements appear in the MB 114 writeup above.

Interpretation. The authors suggest that Gyarub Zangbo and Bordji Badji Mokhtar 001 likely share similar core crystallization histories, with iridium-rich metal pointing to crystallization that proceeded inward, while noting that other models are possible. They conclude that the number of pallasite parent bodies now stands at a minimum of 12, and argue that the shared textures of pallasites from so many different bodies point to a common differentiation and crystallization process rather than a dozen unrelated events.

Where this leaves the science

The carbonaceous connection matters because carbonaceous material is understood to have formed outside the orbit of Jupiter, which would place Gyarub Zangbo's parent body in the outer solar system. Both abstracts report active research rather than settled classification, and neither interpretation is part of the official Bulletin entry, which classifies the meteorite as Pallasite, ungrouped. More on this is on our Gyarub Zangbo origin and science page.

Frequently asked questions

Is this meteorite officially classified? Yes. Gyarub Zangbo is an officially named meteorite, announced as a pallasite in Meteoritical Bulletin 110 (2022) and revised to Pallasite, ungrouped in Meteoritical Bulletin 114 (2026). Offered by Treasure Coast Meteorite Co., IMCA #3323.

What makes Gyarub Zangbo different from other pallasites? Its olivine chemistry, pyroxene content, oxygen isotopes, nickel content and IIF metal affinity together separate it from every established pallasite group.

What is the carbonaceous connection? Jiang and colleagues (2023) described Gyarub Zangbo as an anomalous carbonaceous pallasite on the basis of its mineral chemistry, olivine oxygen and chromium isotopes, and metal chemistry. That would place its parent body in the outer solar system. It is conference research and not part of the official Bulletin classification.

Is it a pyroxene pallasite? Boesenberg and colleagues (2023) identified orthopyroxene in Gyarub Zangbo and described it as the tenth known pyroxene pallasite. The Bulletin records orthopyroxene and augite in its MB 114 reclassification but classifies the meteorite as Pallasite, ungrouped.

Why does the olivine glow when backlit? Olivine is the same mineral as the gemstone peridot, and fresh crystals are transparent to translucent. Weathering gradually turns olivine opaque, which is why some grains stay dark.

What does the epoxy coating do? It stabilizes the olivine and slows the oxidation that darkens crystals over time, without changing how the slice looks.

How scarce is this classification? As of September 2026 the Meteoritical Bulletin database records 17 approved meteorites classified as Pallasite, ungrouped.

Collector significance

At 84.69 grams this slice is sized for a display stand, where its translucency does the work. It pairs that with a classification shared by 17 approved meteorites as of September 2026, and with conference research that places its parent body in the carbonaceous reservoir and identifies it as the tenth known pyroxene pallasite.

This specimen carries serial TC-00043 in the Treasure Coast Meteorite Co. specimen record programme. Its permanent record, with identification data, provenance and photographs, is at Specimen Record TC-00043, and the full index is on the specimen registry.

Meteoritical Bulletin entry: Gyarub Zangbo | Classification: Pallasite, ungrouped | Find, Xizang, China, October 2020 | MB 110 (2022), reclassified MB 114 (2026) | IMCA #3323