Sericho Pallasite Meteorite Slice, PMG, 9.33g, Olivine in Iron-Nickel Matrix

A polished cross-section through an asteroid's core-mantle boundary

This 9.33g slice of the Sericho pallasite puts one of the most structurally interesting meteorite types directly in hand. The polished face exposes a dense mosaic of olivine crystals suspended in a continuous iron-nickel matrix -- the characteristic texture that makes pallasites immediately recognizable and unlike anything else in the natural world. Sericho is notable for its unusually high olivine crystal density, with estimates placing it at 70 to 80% olivine by volume, well above the 50% typical of most pallasites.

The olivine in this specimen has terrestrialized over its time on Earth, shifting from its original green toward amber, brown, and deep black tones. This is a natural and expected consequence of long surface exposure in Kenya's environment, and the resulting color range gives the slice a rich, layered visual character. Metal-rich zones between the crystal clusters show the brushed metallic luster of the iron-nickel alloy, and under magnification the beginning of Widmanstatten structure is visible in areas of coarser metal.

Structure and features

Sericho's olivine crystals are well-rounded to sub-angular, a morphology interpreted as evidence that the crystals were suspended in liquid metal before the pallasite solidified -- a snapshot of the boundary zone between an asteroid's metallic core and its rocky mantle at the moment of cooling. The crystal-metal contacts are clean and sharp on the polished face, with individual crystals ranging from a few millimeters to over a centimeter across.

This slice carries a thin protective epoxy coating applied to both faces to stabilize the olivine crystals and slow further terrestrialization. The terrestrialization of the olivine -- the progressive oxidation and color shift from green toward brown and black -- is visible across the face of this slice. Some crystals retain traces of amber and green in their interiors, visible under direct light at certain angles. The metallic matrix between crystals shows polishing scratches consistent with hand preparation and displays a subdued metallic sheen typical of weathered main group pallasite metal.

Scientific context

Pallasites are among the rarest meteorite types -- fewer than 200 are classified, representing less than 0.2% of all known meteorites. Main group pallasites (PMG) are the largest and best-studied subset, linked geochemically to the IIIAB iron meteorite group and interpreted as samples from the core-mantle boundary of a single differentiated asteroid parent body.

Sericho was formally recognized in 2016 when large masses were acquired from villagers in Isiolo County, Kenya, though local oral history places knowledge of the stones considerably earlier -- camel herders reportedly played on the larger masses as children. The strewn field extends over 45 kilometers, with individual pieces ranging from sub-kilogram fragments to masses as large as 500 kilograms. Learn more about this meteorite type: What Is a Pallasite?

Frequently asked questions

Is this meteorite authenticated? Yes. Sericho is an officially classified meteorite with a Meteoritical Bulletin entry. See the official Meteoritical Bulletin entry for Sericho. This specimen ships with a Treasure Coast Meteorite Co. certificate of authenticity. Offered by Treasure Coast Meteorite Co., IMCA #3323.

Why is the olivine dark rather than green? The olivine in Sericho has undergone terrestrialization -- a natural oxidation process that occurs as olivine crystals react with Earth's atmosphere and moisture over time. Fresh pallasites have transparent green to amber olivine. Sericho's surface exposure has shifted the color toward brown and black in most crystals, with some retaining amber tones in their interiors. This is characteristic of the Sericho find and does not affect the meteorite's authenticity or scientific significance.

What is a main group pallasite? Main group pallasites (PMG) are the largest and most studied pallasite subset, linked geochemically to the IIIAB iron meteorite group. They are interpreted as samples from the core-mantle boundary of a single differentiated asteroid. Sericho belongs to this group.

What is included? The 9.33g polished slice shown, on an acrylic display stand, with a Treasure Coast Meteorite Co. certificate of authenticity. Note: this slice carries a thin protective epoxy coating on both faces.

Collector significance

Pallasites are one of the few meteorite types that require no scientific background to appreciate immediately -- the olivine-in-metal texture is visually self-evident and unlike anything terrestrial. Sericho is the most accessible entry point into pallasite collecting, offering genuine main group pallasite material at a price point that rarer pallasites like Fukang or Imilac cannot approach. For collectors building a type collection, a Sericho slice fills the stony-iron category with a properly classified, documented specimen. Browse our full Stony-Iron Meteorites collection.

Meteoritical Bulletin entry: Sericho | Classification: Pallasite (PMG) | Find, Isiolo County, Kenya, 2016 | Total known weight: ~2,800kg