Wolfkop        29°42.546’S, 19°37.912’E

Northern Cape, South Africa

Find: 2021 Aug 27

Classification: Ordinary chondrite (L5)

History: A single stone discovered by G.F. Lombaard while farming. Brought to attention of R. Gibson via G. Goncalves (USP).

Physical characteristics: A 90.26 g weakly magnetic stone with flattened tetrahedral shape, 7x4.5x2 cm. Upper surfaces are covered by thin (<< 1 mm) brownish black fusion crust that has been chipped away in several shallow pits that expose dark brown oxidized interior; faces intersect in obtuse angles and edges are rounded. Basal surface lacks fusion crust and is formed by an irregular fracture at an acute angle to other faces; it exposes oxidized mid/dark brown granular-textured interior with sub-mm shiny metal flakes and a few <1 mm chondrules.

Petrography: (R.L. Gibson and L.D. Ashwal, Wits) Chondrules are mostly poorly defined, with only a few, large (1.0-2.3 mm) pyroxene-rich (RP, POP) types visible; mostly slightly flattened shapes, but with a few spherical examples present. Irregular metal and troilite grains are up to 0.3 mm in size, with metal showing variable Ni content. Mineralogy: high-Ca Pyx (5%) - low-Ca Pyx (7%) - Ol (70%) - Fsp (6%) - metal (9%) - troilite (3%) and trace chromite, phosphate. The matrix grain size of ~ 50 μm and elongate-polygonal grain shapes indicate significant metamorphic recrystallization. Planar fractures dominate over irregular fractures in Ol and Pyx; Ol shows mosaicism. Fsp shows undulose extinction, PDF and possible maskelynite. Displacements of ~0.1 mm occur along an irregular network of planar to curved fractures that host dark shock veins up to 1 mm wide.

Geochemistry: Mineral compositions and geochemistry: (R.L. Gibson and L.D. Ashwal, Wits) Ol: Fa_25.1±0.6 (24.1-26.5; N=12); low-Ca Pyx: Fs_21.1±0.2 (20.7-21.6; N=14), Wo_1.5±0.2 (1.1-1.8; N=14); high-Ca Pyx: Fs_8.1±0.4 (7.2-8.8; N=10), Wo_46.7±0.4 (44.7-47.2; N=10). Relatively homogeneous Ol and low-Ca Pyx indicate substantial reequilibration.

Classification: Ordinary chondrite (L5), shock stage S4, weathering W2

Specimens: Type specimen (Wits) 82.54 g; cut surface exposes metal flakes up to 2 mm in length in variably weathered (light to dark brown) matrix; remaining surfaces largely intact fusion crust, except for several shallow cm-wide chips. Polished thin section and 1.73 g offcut.