Northwest Africa 13597 (NWA 13597)

(Northwest Africa)

Purchased: 2018 Oct

Classification: Ordinary chondrite (H3)

History: A single stone weighing 411 g was found by an anonymous finder in Western Sahara and purchased in October 2018 at the Turin Fair by Mario Di Martino.

Physical characteristics: The main mass is partially covered by a brown, partially stained fusion crust.

Petrography: (V.Moggi Cecchi, G.Pratesi, S.Caporali UniFi): In the thin section a chondritic texture can be observed, with small PO, POP and RP chondrules and chondrule fragments set in a fine grained matrix. Large olivine crystals in PO chondrules are zoned from core to rim. Olivine is markedly inhomogeneous and Mg-rich in chondrules, while Fe-rich in the matrix. Orthopyroxene in chondrules is inhomogeneous, too, with a core-rim variability. Opaque phases are represented by iron oxides, Fe-Ni alloys and troilite rimming chondrules or present as individual grains scattared in the matrix.

Geochemistry: EMP (V.Moggi Cecchi, G.Pratesi, S.Caporali UniFi); Olivine in both chondrules and matrix (Fa_17.3±6.4Fo_82.7±6.3; n=107; Fe/Mn = 43.9±30.2); low-Ca pyroxene in both chondrules and matrix (Fs_12.1±5.2En_87.2±5.4Wo_0.7±0.3; n=65; Fe/Mn = 23.1±10.2);

Classification: Ordinary Chondrite (H3); S2; W2. Estimated subtype 3.7.

Specimens: The main mass, weighing 411 g, is own by Mario Di Martino; the type specimen, weighing 20.8 g, and one thin section are on deposit at MSN-FI (Inventory # I-3570).