Northwest Africa 14897 (NWA 14897)

Morocco

Purchased: 2017

Classification: Ordinary chondrite (LL7)

History: Purchased by Abdeltif Mechaguen in 2017 at Erfoud, Morocco

Physical characteristics: The main mass, weighing 262 g, is covered by a dark brown fusion crust. A cut face shows the interior is dark brown and appears homogeneous.

Petrography: (P.Manzari, G.Agrosì, G.Tempesta, UniBa; V.Moggi Cecchi, L.Fabrizi, G.Pratesi, Unifi); The thin section of the meteorite appears as a cataclastic breccia consisting of rounded to angular equilibrated chondritic clasts composed by of olivine and orthopyroxene set within a very fine matrix of similar materials. No chondrules were detected in this section. Average clast size is 1300 µm. Average grain size of secondary plagioclase is 150 µm, (n=25). Minor phases include sodic plagioclase, augite and iron oxides, deriving from alteration. Several calcite subparallel veins are visible due to secondary reprecipitation. Accessory phases include tetrataenite, troilite, Ti-chromite, chlorapatite and merrillite. No kamacite nor taenite were detected probably due to marked alteration. A modal estimate performed by means of SEM X-ray mapping maps provided the following results: 48% olivine, 25% low-ca pyroxene, 9% ca-pyroxene, 11% sodic plagioclase, 3% Fe-oxides, 0.6% chromite, 0.4 Cl-apatite, 3% calcite.

Geochemistry: (V.Moggi Cecchi, L.Fabrizi, G.Pratesi, Unifi); Olivine (Fa_31.5±0.3, N = 8: Fe/Mn = 64.3), low-Ca pyroxene (Fs_23.4±0.3Wo_3.3±0.1, N = 4; Fe/Mn = 30.4), augite (Fs_11.0±0.5Wo_40.7±1.2, N = 11; Cr₂O₃ = 1.2 wt.%), plagioclase (Ab_82.3An_15.6Or_2.1, N = 3); Chr. = 56.5 Cr₂O₃, 31.1 FeO, 2.6 TiO₂, 5.5 Al₂O₃, 1.5 MgO, 0.8 V₂O₅, 0.9 MnO, all in Wt.%

Classification: Ordinary chondrite (LL7); S1; W4.

Specimens: 36 g including one polished thin section at MSN-Fi (Inv.# I3690); one polished section at UniBa; main mass with Mechaguen.