Collection
Classification: Achondrite (Primitive) Ungrouped
Observed fall: No
Year found: 2020
City, Country: Northwest Africa
Mass: 4,87 kg
In collection
Weight #1 : 4,61 g
Certificate of authenticity: Yes (1)
NWA 13351 is classified as a primitive achondrite (ungrouped), signifying that it has undergone partial melting and metamorphism yet retains some chemical or textural characteristics of more primitive meteorites. Discovered in Northwest Africa, it does not conform neatly to existing achondrite groups such as Howardites, Eucrites, Diogenites, or angrites, pointing to an unusual formation pathway or distinct parent body. Composed predominantly of compositionally zoned pyroxene oikocrysts (with domains of orthopyroxene, pigeonite and subcalcic augite) enclosing chadacrysts of olivine, together with interstitial devitrified silicic glass plus accessory troilite, pyrrhotite, chromite, very rare kamacite.
Under a light microscope, these stones exhibit a fine-grained, poikilitic igneous texture dominated by zoned pyroxene oikocrysts (orthopyroxene, pigeonite, subcalcic augite) enclosing smaller olivine chadacrysts. In the interstitial regions, one can see devitrified silicic glass along with sulfides such as troilite and pyrrhotite, and opaque chromite grains. Rare kamacite, heavily altered to iron hydroxides, may appear as patchy, reflective remnants, and barite occurs as a secondary mineral. The combination of these minerals in a partially melted, crystallized matrix highlights the rock’s complex thermal and chemical evolution.
