0,43 غرام من نيزك مريخي NWA 15497، من نوع شيرجوتيت

Rarity and Value
Martian meteorite NWA 15497, classified as a basaltic shergottite, represents an exceptionally rare fragment of the Martian crust. Shergottites are among the most scientifically significant meteorites, formed from volcanic activity on Mars and ejected into space by powerful impact events. The presence of maskelynite, formed by shock transformation of plagioclase, together with a complex assemblage of pyroxenes and olivine, confirms both its extraterrestrial origin and its violent history. Such specimens are highly valued by collectors and planetary scientists alike, as they provide direct material evidence of Martian geology and magmatic processes.

Discovery
This specimen was discovered in 2020 in the Sahara Desert of Northwest Africa, one of the world’s most important regions for meteorite recovery. The arid conditions of the desert allow for the preservation and identification of rare extraterrestrial materials. Following its discovery, detailed laboratory analysis confirmed its Martian origin through characteristic Fe/Mn ratios and trace element composition typical of shergottitic meteorites. These geochemical signatures link the specimen directly to volcanic regions on Mars, offering insights into the planet’s internal differentiation and thermal evolution.

Preservation
The slice reveals a fine-grained basaltic matrix composed of low- and high-calcium pyroxenes, olivine, and accessory minerals such as chromite, ilmenite, and sulfides. The transformation of plagioclase into maskelynite records the intense shock pressures experienced during ejection from Mars. Secondary alteration minerals present in minor amounts indicate limited interaction with terrestrial conditions after arrival. The internal structure remains remarkably intact, preserving microscopic details essential for scientific study and providing a rare and tangible connection to the geological history of another planet.

Composition

Maskelynite (shock-transformed plagioclase), low-Ca pyroxene (pigeonite), high-Ca pyroxene (augite), olivine, and accessory phases within a fine-grained basaltic matrix containing chromite, ilmenite, sulfides and minor secondary alteration minerals.

Geochemistry

Plagioclase (An35–55, maskelynite), olivine (Fa25–40), low-Ca pyroxene (En50–60 Fs30–40 Wo5–10), high-Ca pyroxene (Wo30–45), with Fe/Mn ratios consistent with Martian origin, and trace elements showing enrichment in incompatible elements typical of Martian basaltic shergottites.