Gyarub Zangbo Pallasite Meteorite Slice, Ungrouped, 94.90g, Etched and Stabilized

Complete cross-section with etched metal and olivine structure

This 94.90-gram full slice exposes the complete internal architecture of Gyarub Zangbo pallasite: translucent olivine crystals embedded in a nickel-iron matrix that has been acid-etched to reveal the kamacite-taenite intergrowth structure. The etching process brings out the metal's crystallographic texture, creating contrast between the metallic phases and the silicate inclusions. Professional stabilization using Paraloid B-72 on edges and microcrystalline wax on cut faces protects the specimen without adding artificial weight -- no epoxy coating distorts the stated mass.

The slice displays olivine distribution patterns characteristic of pallasite formation at a core-mantle boundary interface. Crystal sizes vary across the section, with some olivines showing the yellow-green peridot coloration that makes pallasites visually distinct among meteorite types. The metal framework shows geometric relationships between adjacent olivine grains, documenting the slow cooling history that allowed large silicate crystals to grow within molten metal.

Surface treatment follows museum conservation protocols. The stated weight represents the meteorite material itself, not added stabilizers. Many commercially available iron and stony-iron meteorites carry thick epoxy coatings that can constitute up to half the listed mass. This specimen's preparation prioritizes scientific integrity and long-term preservation without mass inflation.

Etched metal reveals crystallographic structure

Acid etching removes oxidized surface layers and preferentially attacks kamacite lamellae in the iron-nickel matrix, creating relief that highlights the metal's internal structure. This pallasite shows geometric boundaries where metal grains meet olivine crystals, documenting the specimen's thermal history. The etching brings out subtle variations in nickel content across different metal phases, visible as lighter and darker regions in the matrix.

Olivine crystals appear as discrete grains with irregular margins where they contacted molten metal during formation. Some crystals show fractures from shock events in the parent body's history. The metal framework forms a three-dimensional network around the silicate inclusions, a texture that formed as the olivine-metal mixture solidified at the boundary between a rocky mantle and metallic core.

Stabilization with Paraloid B-72 and microcrystalline wax prevents oxidation of freshly exposed metal surfaces while remaining invisible and reversible. These materials meet conservation standards used by natural history collections worldwide. The treatment does not alter the specimen's appearance or add measurable weight.

Scientific context

Pallasites formed at core-mantle boundaries within differentiated asteroids that underwent complete internal melting and separation into metallic cores and rocky mantles. The olivine-metal mixture characteristic of these meteorites represents material from the interface zone where core and mantle were in contact. Gyarub Zangbo's classification as an ungrouped pallasite indicates it does not match the chemical and isotopic signatures of the main pallasite group, suggesting it originated from a distinct parent body with its own differentiation history.

The olivine crystals in pallasites have the same composition as the gemstone peridot. These silicate minerals formed at high temperatures in the asteroid's mantle, then became incorporated into metallic melt during impact disruption or other processes that mixed core and mantle materials. Slow cooling over millions of years allowed the metal to develop its crystallographic structure while olivine grains remained suspended in the solidifying matrix.

Stony-iron meteorites constitute less than 2% of all meteorite falls, making them significantly less common than pure stone or pure iron types. Pallasites represent the majority of stony-iron specimens but remain rare in collections. For context on meteorite types and formation environments, see Learn About Meteorites.

Frequently asked questions

Is this meteorite authenticated? Gyarub Zangbo is classified in the Meteoritical Bulletin as an ungrouped pallasite found in Tibet in 2020. View the official entry: Gyarub Zangbo. This specimen includes a certificate of authenticity documenting its classification and provenance.

What does "ungrouped" mean for a pallasite? Ungrouped classification indicates this meteorite's chemical and isotopic composition does not match the main pallasite group (PMG) or other established pallasite subgroups. It represents a distinct parent body with its own differentiation and cooling history, making it scientifically significant as a sample from a separate asteroid population.

What stabilization methods were used? Edges are sealed with Paraloid B-72 acrylic resin, and cut faces are treated with microcrystalline wax. Both are standard museum conservation materials that prevent oxidation without adding visible coatings. These treatments are reversible and add no measurable weight to the specimen.

What is included with this specimen? The 94.90g slice and a certificate of authenticity. No display stand is included unless separately noted.

Why is the weight stated as "true weight, no epoxy"? Many iron and stony-iron meteorites sold commercially are coated in thick epoxy that can constitute 30-50% of the stated mass. This specimen uses only conservation-grade stabilizers that do not add artificial weight, so the 94.90g represents actual meteorite material.

Display and collection value

Full slices showing complete cross-sections through pallasite structure command premium positioning in meteorite collections. This specimen's size provides sufficient surface area to display both the olivine distribution pattern and the etched metal structure, while remaining practical for cabinet display. The etching enhances visual contrast between metal and silicate phases, making the specimen's internal architecture immediately apparent.

Ungrouped classification adds scientific interest. While main group pallasites (PMG) represent samples from a single well-studied parent body, ungrouped specimens document the diversity of asteroid differentiation processes across the early solar system. Collectors building reference collections of pallasite types require ungrouped examples to represent this diversity. The Tibet find location adds geographic interest to provenance documentation.

Museum-grade stabilization ensures long-term preservation without the visual degradation that affects untreated iron-bearing meteorites. The absence of epoxy coating allows direct observation of the meteorite's natural surface features. Browse additional specimens in the Stony-Iron Meteorites collection or explore other Premium Specimens.

Meteoritical Bulletin entry: Gyarub Zangbo | Classification: Pallasite (ungrouped) | Find, Tibet, 2020