NWA 17707 Ordinary Chondrite Meteorite Slice, LL4, 27.29g, Complete Cross Section

Full cross section reveals primordial architecture

This complete slice exposes the internal structure of NWA 17707 across its entire 27.29g profile. The polished surface reveals chondrules distributed throughout the meteorite's cross section, preserved within a fine-grained matrix that records conditions from the earliest epoch of the solar system. The LL designation reflects the low total iron and low metal content characteristic of this chemical group, while the type 4 classification indicates thermal processing sufficient to partially recrystallize the matrix without destroying the spherical chondrule structures that formed in the solar nebula.

Found in Algeria in 2024, this specimen represents recently classified material available to collectors while scientific analysis continues. The full slice format provides the maximum viewable area for a specimen of this mass, making chondrule distribution patterns visible across the meteorite's natural dimensions.

Structure and features

Chondrules appear as lighter circular and elliptical structures against the darker groundmass, ranging from submillimeter to several millimeters in diameter. These spherules formed as molten droplets in the solar nebula before accretion into the parent asteroid. The type 4 metamorphic grade indicates heating to approximately 600-700°C on the parent body, sufficient to cause partial equilibration of minerals while preserving chondrule boundaries.

The low metal content typical of LL chondrites results in reduced reflectivity compared to H or L group chondrites. Metal grains present in the matrix appear as small, scattered reflective points rather than the continuous networks seen in higher metal groups. The matrix shows moderate recrystallization, with individual mineral grains visible under magnification but not the complete recrystallization that would characterize higher petrologic types.

Scientific context

LL chondrites derive from a distinct parent asteroid separate from the sources of H and L group ordinary chondrites. Oxygen isotope ratios confirm this separation, though all ordinary chondrite groups formed in similar regions of the early solar system. The type 4 classification places this specimen in a transitional stage between pristine type 3 material and heavily metamorphosed type 6, providing insight into thermal processes within small asteroids during the first tens of millions of years after solar system formation.

Ordinary chondrites constitute approximately 87% of all observed meteorite falls, making them the most common meteorite type reaching Earth. However, recently classified specimens like NWA 17707 expand the available sample set for comparative studies. Learn About Meteorites to understand how chondrules and matrix components record conditions in the protoplanetary disk 4.567 billion years ago.

Frequently asked questions

Is this meteorite authenticated? NWA 17707 is classified in the Meteoritical Bulletin as an LL4 ordinary chondrite. Official classification data: NWA 17707 MetBull entry. This specimen includes a certificate of authenticity documenting its classification and provenance.

What does LL4 mean? LL indicates low total iron (19-22% by mass) and low metal content (1-3% metallic iron), the most iron-depleted of the ordinary chondrite groups. The number 4 represents the petrologic type on a scale from 3 (unmetamorphosed) to 6 (extensively recrystallized), indicating moderate thermal processing at temperatures around 600-700°C.

What is included with this specimen? You receive the 27.29g meteorite slice and certificate of authenticity. No display stand is included.

Why do chondrules form spherical shapes? Chondrules crystallized from molten droplets that achieved spherical geometry through surface tension while floating freely in the solar nebula. Rapid cooling preserved their spherical form before incorporation into the growing asteroid. The preservation of these structures through 4.5 billion years demonstrates that this material never experienced temperatures sufficient to remelt after initial accretion.

Full slice format maximizes scientific utility

Complete slices offer collectors the ability to observe compositional variations across an entire meteorite profile rather than the limited view provided by partial sections or end cuts. This specimen's 27.29g mass represents substantial material for a full slice, providing viewing area comparable to specimens several times heavier when sold as fragments. The Chondrites collection includes specimens across all petrologic types, allowing comparison between primitive and metamorphosed examples from related parent bodies.

LL chondrites remain underrepresented in many collections despite their scientific significance in establishing the compositional range of ordinary chondrite parent bodies. Recent finds from Northwest Africa continue to expand the available sample diversity, with classification work identifying compositional and textural variations that refine models of asteroid thermal evolution. For collectors focusing on ordinary chondrites, specimens representing all three chemical groups (H, L, LL) document the compositional gradient across the asteroid belt region where these objects formed.

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