0,55 غرام من نيزك مريخي NWA 15497، من نوع شيرجوتيت

Rarity and Value
Martian meteorite NWA 15497 is an exceptionally rare basaltic shergottite originating from the surface of Mars. Formed through volcanic activity between 150 and 600 million years ago, this meteorite preserves direct evidence of the geological evolution of the Red Planet. Its mineral composition, including maskelynite formed under extreme shock pressure, together with pyroxenes and olivine characteristic of Martian basalts, makes it highly significant for both scientific research and advanced meteorite collections. Fragments of authenticated Martian material are among the rarest substances available on Earth, valued for their extraterrestrial origin and their connection to planetary exploration.

Discovery
The specimen was recovered in 2020 in the Sahara Desert of Northwest Africa, a region renowned for yielding some of the world’s most important meteorite discoveries. The desert’s dry environment allows extraterrestrial rocks to remain preserved and visually distinguishable against the surrounding terrain. Scientific examination of NWA 15497 confirmed its Martian origin through diagnostic geochemical signatures, including Fe/Mn ratios and trace element enrichment typical of Martian shergottites. These features link the meteorite to volcanic processes on Mars and provide insight into the composition and magmatic history of the Martian crust.

Preservation
This slice preserves a fine-grained basaltic matrix composed of low-calcium and high-calcium pyroxenes, olivine, chromite, ilmenite, and sulfide phases. The presence of maskelynite records the immense shock pressures generated during the impact event that ejected the rock from Mars into space. Minor secondary alteration minerals indicate limited terrestrial weathering after arrival on Earth. The internal structure remains remarkably intact, retaining microscopic mineralogical details essential for planetary science and offering a rare opportunity to study authentic material from another world.

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.