NWA 17707 Ordinary Chondrite Meteorite Slice, LL4, 21.45g, Well-Defined Chondrules

Low-iron chondrite with preserved spherules

This 21.45g slice preserves the spherical chondrules that define chondrite meteorites. The LL classification denotes low total iron and low metallic iron content compared to other ordinary chondrite groups. Type 4 metamorphism altered the original minerals without destroying the rounded chondrule boundaries that remain visible throughout the specimen. The fine-grained matrix surrounding each chondrule records the conditions under which dust and molten droplets condensed in the solar nebula.

NWA 17707 was classified in 2024, adding a recently documented specimen to the LL group. The slice format displays the internal structure across a broad surface area, showing how individual chondrules vary in size and composition within the same parent body fragment.

Chondrule structure and matrix composition

Chondrules appear as circular to elliptical domains ranging from submillimeter to several millimeters across. Each formed as a molten droplet that solidified rapidly in the protoplanetary disk before accretion into the parent asteroid. The LL4 petrologic grade indicates these spherules experienced heating between 600 and 700 degrees Celsius, enough to recrystallize olivine and pyroxene while maintaining recognizable chondrule boundaries.

The groundmass between chondrules contains fine-grained silicate minerals, metal grains, and troilite. Metal content remains lower than in H or L chondrites, giving LL types their characteristic lower density and reduced magnetic response. Dark shock veins may intersect the slice where impact events fractured the parent body.

Scientific context

Ordinary chondrites constitute approximately 80% of all meteorite falls, but the LL group represents only about 10% of that total. These meteorites sample the outer regions of the main asteroid belt where lower iron abundance reflects distance from the inner solar system during planetary formation. The moderate metamorphism preserved in type 4 specimens provides evidence for thermal processing on asteroids too small to differentiate into core-mantle-crust structures.

Chondrules themselves remain one of the most studied features in meteoritics. Their formation mechanism—whether by shock waves, lightning, or other heating events in the solar nebula—continues to drive research into early solar system dynamics. Learn About Meteorites to understand how these objects preserve records from planetary formation.

Frequently asked questions

Is this meteorite authenticated? NWA 17707 received its classification through analysis submitted to the Meteoritical Society. The Meteoritical Bulletin entry confirms the LL4 ordinary chondrite classification. This specimen includes a certificate of authenticity documenting its classification and provenance. Meteoritical Bulletin entry: NWA 17707

What does the LL4 classification mean? LL indicates low total iron (19-22%) and low metallic iron (1-3%), distinguishing this group from higher-iron H and L chondrites. The number 4 represents petrologic type, indicating moderate thermal metamorphism that recrystallized minerals while preserving chondrule outlines.

What is included with this specimen? The 21.45g slice ships with a certificate of authenticity. No display stand is included.

Why do chondrules matter scientifically? Chondrules froze from molten droplets within the first few million years of solar system history. Their mineral composition and cooling rates provide direct evidence for temperatures, timescales, and processes active in the protoplanetary disk before planets formed.

Collector significance

LL chondrites occupy a smaller segment of collections compared to the more common H and L groups, making classified specimens from this series worthwhile additions. The 2024 classification places this material among recently studied falls and finds entering the scientific record. At 21.45g, the slice offers sufficient size to display the chondrule distribution without requiring premium pricing associated with larger slabs.

The slice format suits both desktop display and study under magnification. Collectors building Chondrites suites can use this specimen to demonstrate the structural differences between ordinary chondrite groups. The visible chondrules provide immediate visual interest compared to more metamorphosed type 5 and 6 specimens where these features blur into homogeneous texture.

Meteoritical Bulletin entry: NWA 17707 | Classification: Ordinary Chondrite (LL4) | Find, Algeria, 2024