WHAT IS A PALLASITE
Meteorite Science
Pallasites are stony-iron meteorites containing gem-quality olivine crystals embedded in a metallic iron-nickel matrix. They are among the most visually striking objects in natural science, and among the most sought-after specimens in meteorite collecting.
What Pallasites Look Like
When a pallasite is sliced thin and polished, the result is immediately arresting: rounded to angular olivine crystals ranging from a few millimeters to several centimeters across, suspended in a continuous metallic matrix. The olivine ranges in color from pale yellow to amber, orange, and occasionally green depending on iron content and oxidation state. Where the crystals are sufficiently translucent, a backlit pallasite slice glows with a warm, gemstone quality that no photograph fully captures.
The combination of gemstone and metal in a single natural object, with no terrestrial equivalent and a formation story spanning billions of years, is what makes pallasites enduringly compelling to collectors at every level.
The metallic matrix between the olivine crystals often shows the Widmanstätten pattern when etched, the same interlocking crystal structure of kamacite and taenite visible in iron meteorites. Its presence confirms the slow cooling that produced both the metallic architecture and the large, well-formed olivine crystals. Everything visible in a polished pallasite slice is a record of geology that happened inside an asteroid billions of years ago.
Gyarub Zangbo ungrouped pallasite, 94.90g. The etched metallic matrix reveals kamacite-taenite intergrowth structure alongside the embedded olivine crystals.
Gyarub Zangbo ungrouped pallasite, 64.00g. Backlit to show the translucency of the olivine crystals. The amber glow is characteristic of iron-bearing forsteritic olivine in a thin polished section.
Where Pallasites Come From
The most widely accepted model for pallasite origin places them at the core-mantle boundary of differentiated asteroids, the zone where the metallic iron-nickel core met the olivine-rich rocky mantle. When a differentiated asteroid was shattered by a collision, boundary material was exposed, producing the mixture of metal and olivine we see in pallasite slices.
This model is well-supported but has been complicated by more recent geochemical work. Oxygen isotope compositions suggest that some pallasites may come from different locations within the same parent body, or from different parent bodies entirely. The classification reflects this complexity.
The Olivine in Pallasites
Pallasite olivine is a magnesium-iron silicate with a composition that plots distinctly from terrestrial olivine. The crystals are often well-formed and large, products of slow crystallization at the core-mantle boundary of a large asteroid over geological time. In fresh specimens, pallasite olivine is transparent to translucent. Over time, exposure to terrestrial weathering causes the olivine to oxidize and become opaque and brownish. Collectors prize specimens with intact, transparent crystals.
In some pallasites, the olivine shows a rounded, corroded morphology that suggests partial dissolution by the surrounding metallic melt. This texture is interpreted as evidence that the olivine crystals were suspended in liquid metal before the pallasite solidified, a preserved record of the core-mantle boundary in a molten state. In others, the crystals are sharply angular, suggesting a different thermal history or more rapid solidification.
The translucency of pallasite olivine is sensitive to weathering. Desert-found pallasites that have been on Earth's surface for thousands of years may show degraded or opaque olivine even when the metallic matrix is well-preserved. Fresh or low-weathering specimens with intact, glassy olivine command a significant premium over otherwise similar material with clouded crystals.
Notable Named Pallasites
Several pallasites are well-known enough to be recognized by their locality names among collectors. Each has a distinct visual character and scientific story.
Pallasites as Collector Specimens
Pallasites occupy a unique position in meteorite collecting. They require more preparation than most meteorite types to display effectively. A raw pallasite individual shows little of what makes the material exceptional. The standard presentation involves cutting, lapping flat, and polishing to optical quality on at least one face, with optional etching of the metallic matrix to reveal the Widmanstätten structure. Some collectors prefer backlit display in lightboxes or frames, which transforms a polished slice into a genuinely luminous object.
Prices vary considerably based on olivine transparency, crystal size, total known weight of the parent meteorite, and presentation quality. Main group pallasites from large finds like Sericho are accessible at modest prices. Material from small-find or scientifically rare pallasites like Esquel or ungrouped specimens commands significantly higher values per gram.
Browse Pallasite Specimens
Frequently Asked Questions
Are pallasites rare?
Yes. Stony-iron meteorites as a class represent less than 2% of all recovered meteorites, and pallasites are a subset of that already rare category. Some individual pallasites, particularly those from small finds or with exceptional olivine quality, are genuinely scarce on the collector market.
Why do pallasites have olivine crystals?
Pallasites formed at the boundary between the metallic core and the silicate mantle of a differentiated asteroid. The olivine crystals are mantle material that became intermixed with the metallic core material during the violent processes that followed the asteroid's disruption by collision. The result is a permanent record of the interface between metal and rock inside an ancient planetary body.
Can pallasite olivine crystals fall out?
Yes. Olivine is susceptible to weathering and can degrade or detach over time if specimens are stored in humid conditions or exposed to moisture. Well-prepared pallasites with stabilized matrices tend to retain their crystals better. Desert-found specimens that have been on Earth's surface for a long time sometimes show voids where crystals once were.
What is a PMG pallasite?
PMG stands for pallasite main group, the dominant chemical grouping among pallasites. Most commercially available pallasites belong to this group. The designation appears in Meteoritical Bulletin entries and on certificates of authenticity for classified main group specimens.
How should pallasite slices be stored?
In a low-humidity environment, away from moisture sources. The metallic matrix is susceptible to oxidation, and the olivine crystals can degrade if exposed to sustained moisture. A sealed display case with silica gel desiccant is ideal. Periodic application of Renaissance Wax or food-grade mineral oil to the metallic surface helps slow oxidation on etched faces.
