Northwest Africa 13596 (NWA 13596)

(Northwest Africa)

Purchased: 2018 Oct

Classification: Ordinary chondrite (H3)

History: A single stone weighing 90 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 completely covered by a dark-brown fusion crust.

Petrography: (V.Moggi Cecchi, G.Pratesi, S.Caporali UniFi): The thin section displays a chondritic texture, with various chondrule types (PO, POP and RP) set in a fine grained matrix and ranging from 400 to 1200 μm. PO chondrules display zoned olivine crystals. POP chondrules display olivine grains and elongated pyroxene grains. Olivine is inhomogenesous and Mg-rich in chondrules, while Fe-rich in the matrix. Orthopyroxene in chondrules is inhomogeneous, with a core-rim variability. Iron oxides, Fe-Ni alloys and troilite are the main opaque phases and can be found as individual grains scattared in the matrix or rimming chondrules.

Geochemistry: EMP (V.Moggi Cecchi, G.Pratesi, S.Caporali UniFi); Olivine in both chondrules and matrix (Fa_17.5±7.9Fo_82.5±7.7; n=; Fe/Mn = 45.6±28.4); low-Ca pyroxene in both chondrules and matrix (Fs_12.0±5.5En_87.1±5.4Wo_0.9±0.4; n=65; Fe/Mn = 17.5±11.3);

Classification: Ordinary Chondrite (H3); S3; W3, estimated subtype 3.5 based on Fa and Fs values and standard deviations.

Specimens: The main mass, weighing 90 g, is own by Mario Di Martino; the type specimen, weighing 18.1 g, and one thin section are on deposit at MSN-FI (Inventory # I-3569).