Northwest Africa 13297 (NWA 13297)

Algeria

Purchased: 2020

Classification: Ordinary chondrite (LL3)

History: A sample comprised of many weathered pieces weighing 1973 g were found by meteorite prospectors in Algeria and sold to Mohamed Elguirah in Laayoune, Morocco. John Higgins and Carlos Muñecas Muñoz purchased the samples in 2020.

Physical characteristics: Most samples are tabular in shape. One sample has an irregular ovoid shape with a dark brown weathered exterior. The cut face of the irregular sample shows a fresh, unweathered interior composed of abundant chondrules surrounded by fine-grained sulfide rims. FeNi grains occur within the interiors of chondrules. The unweathered interior is surrounded by a well-developed weathering rind with concentric cracks that surround unweathered interior. Material in the weathering rind is identical to tabular samples.

Petrography: Description and classification (A. Love, App) Sample has a chondritic texture composed of distinct, close-packed chondrules with an average apparent diameter of 763 μm (n=77) set within an opaque fine-grained, clastic matrix. Chondrules are surrounded by fine-grained rims of sulfide and have mesostasis commonly composed of isotropic glass and devitrified glass (dominant). Additional minerals are troilite, apatite and secondary calcite.

Geochemistry: (A. Love, App) Olivine (Fa_16.7±10.2 (Fa_0.6-30.1), Fe/Mn=36.6±11.8, n=12. Cr₂O₃ in type II chondrules has an average of 0.22±0.10, n=10); low Ca-pyroxene (Fs_12.9±10.1Wo_0.9±0.6 (Fs_1.7-34.5Wo_0.2-2.5), n=10).

Classification: Ordinary chondrite (LL3, C-S3, W1-3) Based on chondrule size and magnetic susceptibility this sample is an LL chondrite. Estimated subtype for this sample is between 3.15 and 3.2 based on unequilibrated compositions, presence of isotropic glass mesostasis (<3.3), yellow CL in chondrule mesostasis (3.1-3.2) and presence of red luminescence in chondrule olivine <3.5) and low CL of matrix (>3.1).

Specimens: John Higgins holds 1213 g including the 250 g main mass and Carlos Muñoz holds and additional 760 g of tabular fragments. Many spalled tabular fragments and an endcut weighing a total of 130 g are and a polished thin section are on deposit at App.