Description:
NWA 11905 is a unique, newly classified LL3.10-5 tri-lithology; the first of its kind. Recently approved by NomCom, this exotic stone was analyzed by Dr. Carl Agee (UNM), where extensive testing determined it to be the first of its kind LL3.10-LL3-LL5 Polymict Breccia. The LL3 host lithology suspends beautiful LL3.10 and LL5 lithologies frozen in matrix.
This is the only approved meteorite classified as an LL3.10-5 (LL-group Polymict Breccia). This extremely rare stone is only available from the Natural History Laboratory.
The UNM collection proudly hosts a full slice of this rare meteorite in their collection; a gem along side some of the most prized specimens known to science.
Scientific write-up by Dr. Carl Agee:
Physical characteristics: Single stone. Saw cuts show a breccia of visually different chondrite clasts set in a host chondrite groundmass. Some of the clasts appear to be texturally equilibrated with less distinct chondrules, whereas others resemble type-3 lithologies with densely packed chondrules. The host groundmass contains numerous large, distinct, well-formed chondrules.
Petrography: (C. Agee, UNM) Microprobe examination of several polished mounts shows three group LL lithologies present: Lithology 1 is LL3.10; Lithology 2 is LL5; and Lithology 3 makes up the host groundmass and is LL3. Lithology 1 has numerous porphyritic chondrules, most with mesostasis or glass and abundant opaque matrix. The apparent mean chondrule diameter in Lithology 1 is 900±400 μm, n=31. Lithology 2 has texturally equilibrated chondrules and plagioclase grains up to 25 μm. Lithology 3 (host) has numerous porphyritic chondrules, many with mesostasis, fine-grained plagioclase also detected.
Geochemistry: (C. Agee, UNM) Lithology 1: all olivine Fa14.0±11.0, Fe/Mn=41±15, n=44; ferroan chondrule olivine Fa17.3±9.9, Fe/Mn=45±13, Cr2O3=0.32±0.20 (wt%), n=35; low-Ca pyroxene Fs11.1±10.0Wo1.1±0.8, n=12. Lithology 2: olivine Fa30.7±0.6, Fe/Mn=60±2, n=19; low-Ca pyroxene Fs24.9±0.3Wo1.3±0.9, n=12. Lithology 3: olivine Fa27.9±3.0, Fe/Mn=57±15, n=8; low-Ca pyroxene Fs24.3±1.8Wo2.1±3.5, n=4.
Classification: Ordinary chondrite (LL3.10-LL3-LL5), LL-group polymict breccia. Type 3.10 for Lithology 1 is based on the mean value of Cr2O3 in ferroan chondrule olivine and the 1-sigma standard deviation, (Grossman and Brearley, 2005), a similar petrologic type to NWA 1756 (LL3.10), NWA 3127 (LL3.10), RC 075 (H3.10), and MET 96503 (L3.10). Estimated type for Lithology 3 is 3.8/3.9 based on the scatter in olivine composition.
