Sinawan 005 Rumuruti Meteorite Slice, R5-6, 22.82g, Dual Lithology Zones

Dual lithology R-chondrite with visible compositional boundaries

This Sinawan 005 slice displays sharp boundaries between light and dark lithologies within a single 22.82g specimen. The contrasting zones represent different thermal metamorphic grades preserved in the same meteorite, a diagnostic feature of R5-6 classification. The light region shows coarser-grained recrystallization while the darker zone retains finer textures, visible across the entire face of the slice. Only three specimens of Sinawan 005 exist in collections worldwide.

Rumuruti-type chondrites constitute less than 0.5% of all classified meteorites. This specimen was recovered in Libya in 2023 and classified through analysis documented in the published scientific literature. The R5-6 designation indicates metamorphic grades straddling petrologic types 5 and 6, reflecting complex thermal history in the parent body interior.

Structure and features

The slice reveals two distinct lithologic domains separated by a visible transition zone. The lighter region occupies approximately 60% of the specimen face and displays homogenized mineral grains consistent with type 6 metamorphism. The darker domain retains partial chondrule structure and finer matrix material characteristic of type 5. This textural heterogeneity within a single stone indicates impact mixing or incomplete thermal equilibration on the parent body.

Olivine grains in both zones show the iron-rich composition typical of Rumuruti chondrites, distinguishing them from ordinary and carbonaceous types. The slice surface has been prepared to highlight the boundary between lithologies without obscuring internal structure. Minor weathering fractures cross both domains, consistent with terrestrial residence time in the Sahara.

Scientific context

Rumuruti chondrites formed on a distinct parent body separate from ordinary, enstatite, and carbonaceous chondrite sources. Oxygen isotope data place R-chondrites outside the terrestrial fractionation line, confirming a unique origin. The high oxidation state and iron-rich olivine composition suggest formation in a different region of the early solar system compared to more common meteorite types.

The dual lithology nature of Sinawan 005 specimens indicates the parent body experienced localized heating events or impact-driven mixing after initial formation. Type 5-6 metamorphism requires sustained temperatures between 700 and 950 degrees Celsius, likely achieved through internal radiogenic heating or large impact events. Understanding these transitional types helps constrain thermal evolution models for small planetary bodies. Learn About Meteorites to explore how different chondrite groups relate to solar system formation processes.

Frequently asked questions

Is this meteorite authenticated? Sinawan 005 is classified as Rumuruti (R5-6) in the Meteoritical Bulletin Database. You can verify the classification at Meteoritical Bulletin entry for Sinawan 005. A certificate of authenticity documenting the classification accompanies this specimen.

What does R5-6 classification mean? The R designation identifies this as a Rumuruti-type chondrite, a rare group with iron-rich olivine. The 5-6 indicates the specimen contains material from two metamorphic grades: type 5 with partial recrystallization and type 6 with complete thermal equilibration. This dual classification reflects heterogeneous heating history preserved in the meteorite.

What is included with this specimen? You receive the 22.82g slice shown in the photographs and a certificate of authenticity. No display stand is included.

Why are there only three known specimens? Sinawan 005 was found and classified in 2023, making it a recent discovery. The total known weight recovered was limited, and only three individual specimens have been documented. This reflects both the scarcity of the fall and the rarity of R-chondrites in general.

How should I display this dual lithology specimen? The contrasting zones are visible from both sides of the slice. Positioning under directional lighting enhances the boundary between light and dark domains. The specimen displays well in standard meteorite holders or acrylic stands that allow viewing of the entire prepared surface.

Collector significance

Rumuruti chondrites represent less than 0.5% of the meteorite collection population, making any R-type specimen a priority acquisition. Sinawan 005 adds documented scarcity with only three known specimens worldwide. The dual lithology feature provides immediate visual distinction from uniform chondrites and offers a tangible example of incomplete thermal processing.

The 22.82g size permits detailed examination of both lithologic zones while remaining display-friendly for cabinet collections. Scientific documentation in published literature adds research provenance beyond standard Meteoritical Bulletin classification. Collectors focusing on Chondrites or building comprehensive type collections will find limited future opportunities to acquire Sinawan 005 material. For those interested in diverse compositional groups, explore our Stony Meteorites collection.

Meteoritical Bulletin entry: Sinawan 005 | Classification: Rumuruti (R5-6) | Find, Libya, 2023