NWA 18048 Eucrite-pmict Meteorite End Cut, 1530.00g, Main Mass, Mixed Clast Structure

Main mass from a classified polymict eucrite

This 1530.00g end cut represents the main mass of NWA 18048, a classified polymict eucrite recovered in Northwest Africa in 2024. The specimen preserves the principal recovered stone from this fall, giving it curatorial significance beyond its scientific classification. The end cut format exposes a fresh internal surface showing the mixed clast structure characteristic of polymict eucrites while maintaining the bulk and physical presence of the original stone.

Polymict eucrites form through impact processes that mix multiple generations of crustal material on a differentiated parent body. This specimen displays that process through varied clast sizes and compositions distributed through a finer-grained matrix. The exposed face shows the textural complexity that separates polymict eucrites from uniform monomict basaltic types, making this specimen both visually engaging and scientifically informative.

Clast distribution and matrix structure

The exposed surface reveals distinct eucritic clasts ranging from millimeter to centimeter scale, set within a darker, finer-grained matrix. These clasts represent fragments of earlier basaltic crust that were disrupted, transported, and reassembled through impact gardening on the parent body surface. The matrix consists of comminuted eucritic material and impact melt products that cemented the clasts together during subsequent heating and lithification.

The variation in clast size, texture, and boundary sharpness across the specimen reflects multiple impact events rather than a single brecciation episode. Some clast boundaries show clean separation while others grade into the surrounding matrix, indicating different thermal and shock histories for individual fragments. This textural heterogeneity makes polymict eucrites valuable for understanding long-term surface evolution on small differentiated bodies.

Formation on a differentiated asteroid

Eucrites belong to the HED achondrite group and formed through basaltic volcanism on a differentiated parent body, widely linked to asteroid 4 Vesta. NASA's Dawn mission confirmed Vesta's basaltic crust and impact history, providing direct evidence for the connection between HED meteorites and this 525-kilometer-diameter asteroid. Polymict eucrites specifically record the reworking of that crust through impact processes over geological time.

The mixed clast assemblage in this specimen represents multiple generations of crustal material, indicating that Vesta's surface underwent repeated impact disruption and reassembly. This process produced a regolith layer composed of brecciated fragments rather than intact bedrock, similar to the lunar highlands but on a body with distinct compositional and thermal history. Understanding these polymict assemblages helps constrain impact flux rates and crustal evolution on differentiated asteroids. Learn more about meteorite types in our Learn About Meteorites guide.

Frequently asked questions

Is this meteorite authenticated? NWA 18048 is classified by the Meteoritical Society as a polymict eucrite. The classification data can be verified through the Meteoritical Bulletin entry: NWA 18048. This specimen includes a certificate of authenticity documenting its classification, weight, and provenance.

What does polymict mean in this classification? Polymict indicates the specimen is a breccia containing multiple clast types rather than a single uniform rock. In eucrites, this reflects impact mixing of different crustal fragments on the parent body surface. The "pmict" designation distinguishes these mixed specimens from monomict eucrites that preserve uniform basaltic textures.

What is included with this specimen? The specimen weighs 1530.00g and includes a certificate of authenticity. No display stand is included with this main mass specimen due to its size and weight.

Why is this called the main mass? The main mass is the largest single piece recovered from a meteorite fall or find. It represents the principal stone and carries added curatorial significance in collections. Main masses are often retained by institutions or serious collectors because they preserve the bulk and physical integrity of the original meteorite.

How should I display a specimen this size? At 1530g, this specimen benefits from a stable horizontal orientation that shows the exposed clast structure. The end cut format provides a natural display face while the opposite surface preserves the original exterior. Custom display solutions work better than standard stands for specimens of this mass.

Significance for HED collectors

Main mass specimens occupy a distinct position in meteorite collecting because they represent the anchor piece from a given recovery. When that main mass is also a classified polymict eucrite from the HED suite, it combines curatorial importance with scientifically complex structure. This specimen serves collectors who prioritize both physical scale and scientific content over small representative fragments.

The 1530g mass makes this piece suitable for advanced collections where display impact and scientific integrity both matter. The exposed clast structure provides ongoing visual interest rather than presenting as a homogeneous surface, and the polymict classification places it within the broader context of Vestan crustal evolution. Explore more HED specimens in our Eucrites collection, or view related material in our HED Meteorites category.

Meteoritical Bulletin entry: NWA 18048 | Classification: Eucrite-pmict | Find, Northwest Africa, 2024