Feldspathic Breccias
Name
*click on the Name for more information
Structure Class
achondrites
Chemical Class
Lunar (feldsp. breccia)
Country
Year found
2022
Mass
2.09 kg
[Museum Collection]
(1) 10.46g
History: Many small, similar-appearing stones were found together in Algeria on March 24, 2022, by a team represented by David Lehman. Some of the material was also acquired by John Higgins, Jasper Spencer, Ziyao Wang, and Preston Allen. Physical characteristics: The stones (total 2090 g) lack fusion crust and have light brown weathered exteriors. Fresh interiors are medium gray with diffuse small white clasts and rare tiny metal grains visible. Petrography: (A. Irving, UWS and P. Carpenter, WUSL) Electron microprobe analyses were conducted on small slices from four separate stones. Although there is some mineralogical and compositional heterogeneity among these pieces, all consist of mineral clasts of calcic plagioclase (predominantly anorthite but also some sodic bytownite), olivine, low-Ca pyroxene and augite within a very fine grained, sparsely microvesicular matrix containing Ti-chromite, troilite, kamacite and minor secondary barite. Geochemistry: Calcic plagioclase (An70.7-97.7Or1.1-0.0, N = 12), olivine (Fa22.9-49.5, FeO/MnO = 86-114, N = 14), low-Ca pyroxene (23.1-26.5Wo4.3-4.4, Fe)/MnO = 56-57, N = 2), pigeonite (Fs22.0-32.3Wo6.9-12.5, FeO/MnO = 52-61, N =7), augite (Fs11.9-19.4Wo35.8-38.6, FeO/MnO = 42-52, N = 5). Classification: Lunar (feldspathic breccia). Specimens: 60.2 g including a composite four-slice polished thick section at UWB; 1064 g with Mr. D. Lehman; 483 g with Mr. J. Higgins and Mr. J. Spencer; 137 g with WangZ; 431 g with Mr. P. Allen.
Name
*click on the Name for more information
Structure Class
achondrites
Chemical Class
Lunar (feldsp. breccia)
Country
Year found
2022
Mass
7.21 kg
[Museum Collection]
(1) 4.68g (2) 4.56g (3) 4.38g (4) 4.20g
(5) 3.90g (6) 3.59g
History: Hundreds of stones were reportedly found in March 2022 and subsequent months by meteorite hunters within the Bechar region, Algeria. About 7 kg of this material were bough by Mohamed Ali Loud, Miguel Angel Contreras Gomez, and Viktor Plamenov Ivanov Physical characteristics: The material occurs in two different varieties. Samples found on the surface have light brown exteriors. The ones found buried have whitish exteriors with orange caliche. All stones lack fusion crust. Interiors are predominately gray with dark gray and white clasts. Some metal grains are macroscopically visible. Petrography: (K. Metzler, IfP) Fine-grained polymict breccia, consisting of mineral fragments (mainly plagioclase, pyroxene, Ca-rich pyroxene, and olivine) and a few anorthositic lithic clasts, set in a compacted fine-grained matrix. The matrix partly represents a crystallized melt. Subrounded units of clast-rich impact melt rocks are admixed. Accessories are ilmenite, troilite, and Ni-bearing metal; one zircon grain (~25 µm) was observed. Geochemistry: Mineral compositions and geochemistry: Olivine Fa28.3±6.4 (Fa17.5-40.1); mean Fe/Mn (at.): 112; n=8. Low-Ca pyroxene Fs26.4±4.0Wo4.1±2.1 (Fs20.0-31.6Wo1.8-8.3); mean Fe/Mn (at.): 67; n=11. Ca-rich pyroxene Fs17.9±0.8Wo39.4±1.4 (Fs17.3-18.4Wo38.4-40.3) mean Fe/Mn (at.): 48; n=2. Plagioclase An96.2±0.8Or0.1±0.1 (An95.4-98.0Or0.0-0.3); n=11. Classification: Lunar (feldspathic breccia), based on texture and mineral chemistry
Name
*click on the Name for more information
Structure Class
achondrites
Chemical Class
Lunar (feldsp. breccia)
Country
Year found
2011
Mass
292 g
[Museum Collection]
(1) 3.71g
History: Found by a prospector in December 2011. Physical characteristics: Angular 5 × 4 × 3 cm stone (292 g) with shiny, reddish exposure surface and bluish-grey basal surface. On surface ~5 mm rounded, knobby, yellowish-white to dark grey, partly melted clasts are embedded in a flow-textured groundmass, which has abundant, sub-mm vesicles. Petrography: (A. Wittmann and P.Carpenter, WUSL) Melt rock with flow texture of aphanitic melt enclosing 5 to <0.5 mm size clasts of feldspar-rich rocks. All clasts are recrystallized but retain outlines of original textures of poikilitic to subhedral mafic silicates in plagioclase-dominated groundmass. Groundmass plagioclase forms dense masses of tabular, felty textured crystals with <10 μm skeletal pyroxene crystals filling interstices. Olivine occurs up to 50 μm, zoned, subhedral crystals in the melt groundmass, and in partly assimilated clasts is overgrown with augite that poikilitically encloses acicular plagioclase, silica-rich mesostasis and euhedral, up to 30 μm armalcolite crystals. Accessory troilite occurs in the melt groundmass as round to oval,
Name
*click on the Name for more information
Structure Class
achondrites
Chemical Class
Lunar (feldsp. breccia)
Country
Year found
2019
Mass
57.41 kg
[Museum Collection]
(1) 4.89g
History: Beginning in December 2019 many similar dark stones were found together in the Kidal region of Mali, close to the border with Algeria. One very large stone (40026 g), another stone (4037 g) and 44 smaller stones (combined weight 3642 g) (total weight 47705 g) were purchased by Aziz Habibi in January 2020 from an Algerian dealer and subsequently acquired by Darryl Pitt. Independently, ten other stones of the same distinctive material (combined weight 8536 g) plus many smaller fragments (combined weight 1169 g) were purchased by Mbark Arjdal in February and March 2020 from a relative of the same Algerian dealer. Physical characteristics: All specimens (many of which have a flattened slab-like form) lack fusion crust and exhibit medium-brown, "knobby" exterior surfaces. Interiors of stones have an overall tan to pinkish hue with obvious light gray, dark gray and whitish clasts plus some visible small grains of metal. Petrography: (A. Irving, UWS and P. Carpenter, WUSL) Two separate endcut specimens were studied. Both are samples of the same breccia material, composed of mineral clasts of anorthite, olivine, pigeonite, subcalcic augite, augite and orthopyroxene, plus sparse lithic clasts of spinel troctolite, set in a fine grained microvesicular matrix containing accessory altered kamacite, troilite, taenite and pentlandite. Secondary calcite is present pervasively in one of the two specimens studied and in places may be replacing original glass. Olivine grains in both studied specimens have been partially replaced by inhomogeneous phyllosilicate-rich assemblages, which apparently are hydroxylated (as evidenced by systematically low oxide analytical sums of 88-90 wt.% and absence of measurable F and Cl), and which are very Mn-deficient (yielding very elevated FeO/MnO ratios in the range 150-250). Troctolitic clasts are composed predominantly of anorthite and olivine with accessory Cr-pleonaste, low-Ca pyroxene and/or higher-Ca pyroxene. Geochemistry: Olivine (Fa17.3-32.1, FeO/MnO = 76-100, N = 15), anorthite (An95.4-99.0Or0.2-0.0, N = 7), pigeonite (Fs18.2-26.8Wo12.4-4.7, FeO/MnO = 47-54, N = 6), orthopyroxene (Fs16.0-21.6Wo2.2-3.7, FeO/MnO = 51-66, N = 4), subcalcic augite (Fs15.9Wo31.0, FeO/MnO = 41), augite (Fs7.6-7.9Wo42.9-45.6; Fs13.8Wo38.9; FeO/MnO = 36-48, N = 3). Troctolite clast: olivine (Fa18.2-21.2, FeO/MnO = 84-92, N = 4), anorthite (An97.7Or0.0), pleonaste (mg = 0.721, cr = 0.093). Classification: Lunar (feldspathic regolithic breccia, partially hydrothermally-altered). Specimens: 37.6 g in the form of two polished endcuts at UWB; remainder with DPitt and Mr. M. Arjdal.
Name
*click on the Name for more information
Structure Class
achondrites
Chemical Class
Lunar (feldsp. breccia)
Country
Year found
2020
Mass
3.71 kg
[Museum Collection]
(1) 2.72g (2) 2.66g (3) 2.13g
History: These two stones were found by meteorite hunters driving off-road between Tabelbala, Algeria, and the Erg Chech 002 find locality. Nearest towns to this find are Adrar and Tamentit, Algeria. Physical characteristics: Two stones, identical in appearance, (2035 and 1675 g) were found together. This is a fragmental breccia with white plagioclase megacrysts and lithic clasts set in a dark shocked matrix. Plagioclase megacrysts are up to two centimeters in length and are translucent in thinly sliced slabs. No fusion crust is present. Petrography: (C. Agee, UNM) Electron microprobe analysis and imaging reveals a fragmental breccia with large, sometimes euhedral anorthite crystals (megacrysts). The megacrysts appear to be shock-mosaicized or recrystallized with a significant amount of dark and light inclusions present, some of the observed inclusion veining in the megacysts is possibly maskelynite. The compositions of the plagioclase megacrysts are slightly more anorthitic than the groundmass plagioclase fragments, although there is compositional overlap between the two that is within microprobe error. This is possibly a monomict breccia since the section analyzed had only one coherent population of pyroxenes and olivines that appear to be related by equilibrium igneous crystallization. The olivine and pyroxene compositions are similar to that in ferroan anorthosites. Shock melt veins with vesicles were observed. Minor opaque phases are ilmenite and chromite. Geochemistry: (C. Agee, UNM) Plagioclase megacrysts An97.2±0.7Ab2.6±0.3Or0.2±0.1, n=6; groundmass plagioclase An96.5±0.3Ab3.2±0.3Or0.2±0.1, n=6; low-Ca pyroxene Fs28.2±5.9Wo5.6±3.1, Fe/Mn=59±6, n=6; augite Fs18.7±0.4Wo43.2±1.5, Fe/Mn=48±1, n=2; olivine Fa36.7±10.1, Fe/Mn=95±3, n=9; shock melt vein SiO2=43.6±0.4, Al2O3=31.1±0.8, FeO=3.7±0.6, MgO=3.3±0.5, MnO=0.05±0.02, CaO=17.3±0.1, Na2O=0.32±0.05 all wt%, n=3. Classification: Lunar feldspathic breccia with plagioclase megacrysts. Mafic minerals similar in composition to that present in ferroan anorthosies. Specimens: 25.8 g on deposit at UNM, Mark Lyon holds the main masses.